You can follow all the latest on the Texas school shooting here.
Who was the teacher who died?
Mireles, the teacher who was reportedly killed, was in her early 40s and had a daughter in college, according to her page on the school district’s website.
She had been an educator for 17 years. The page quoted her as saying: "I love running, hiking, and now you just might see me riding a bike!!"
Her aunt, Lydia Martinez Delgado, told the New York Times her niece was “very loved” and "was the fun of the party”.
Adult victim named as fourth grade teacher Eva Mireles
The teacher killed in Tuesday's attack has been named as Eva Mireles according to KSAT-TV, the local ABC News affiliate in the San Antonio area.
The network reports that she worked at Robb Elementary as a fourth grade teacher, instructing pupils between 9-10 years old.
Obama wiped away tears in 2012 as he spoke about the children killed at Sandy Hook Elementary SchoolImage caption: Obama wiped away tears in 2012 as he spoke about the children killed at Sandy Hook Elementary School
We have a statement now from former President Barack Obama.
“Across the country, parents are putting their children to bed, reading stories, singing lullabies - and in the back of their minds, they’re worried about what might happen tomorrow after they drop their kids off at school, or take them to a grocery store or any other public space,” he says.
He and his wife Michelle "grieve" for the families, he said, adding: "We’re also angry for them.
"Nearly ten years after Sandy Hook - and ten days after Buffalo - our country is paralysed, not by fear, but by a gun lobby and a political party that have shown no willingness to act in any way that might help prevent these tragedies.”
“It’s long past time for action, any kind of action," says Obama.
In 2015, as he was preparing to leave office, the Democratic president told BBC News that his administration's failure to enact new gun reforms was the greatest frustration of his presidency.
"For us not to be able to resolve that issue has been something that is distressing," he told the BBC's Jon Sopel.
What has Biden done to tackle gun violence?
Getty ImagesCopyright: Getty Images
Biden holds the components of a "ghost gun" at a White House event in AprilImage caption: Biden holds the components of a "ghost gun" at a White House event in April
Biden has previously said he wants to see a ban on assault weapons, high-capacity magazines and mandatory background checks for all gun sales.
But so far he has been unable to persuade Congress to pass "common sense" gun reforms, and has instead focused on executive actions that he can take without congressional approval.
His administration has focused its efforts on the sale of untraceable do-it-yourself "ghost gun" kits.
In April, he signed an order requiring the kits to have serial numbers - legally making them a firearm.
'They watched friends die as if they're on a battlefield'
Speaking in the White House Roosevelt Room, President Biden asked Americans to pray for the children of Uvalde tonight.
He began his remarks by praising the "beautiful, innocent" children killed in Uvalde, and their traumautised pupils who watched "friends die as if they're in a battlefield".
"They'll live with it for the rest of their lives," he said.
After his brief remarks concluded, he didn't answer a journalist's question about whether he'll travel to Texas.
It comes just after he went to Buffalo, New York, last week to meet victims and survivors of a shooting at a grocery store in the city.
Biden: 'Why are we willing to live with this carnage?'
ReutersCopyright: Reuters
"Why are we willing to live with this carnage? Why do we keep letting this happen? Where in God's name is our backbone?" Biden asks.
"It's time to act," he said. "We can do so much more, we have to do more."
Biden: 'When will we stand up to the gun lobby?'
Biden asks: "When in God’s name are we going to stand up to the gun lobby?”
"I am sick and tired of it. We have to act," he said speaking from the White House. "Don't tell me we can't have an impact on this carnage.
"The idea that an 18-year-old kid can walk into a store and buy two assault weapons is just wrong.
"These kinds of mass shootings rarely happen anywhere else in the world."
BreakingBiden on the grief of losing a child
"To lose a child is like having a piece of your soul ripped away," US President Joe Biden said from the White House.
"There's a hollowness in your chest, you feel like you're going to be sucked into it... It's never quite the same."
He was joined by his wife, First Lady Jill Biden, as he spoke.
ReutersCopyright: Reuters
Uvalde vigil attendees weep and pray
Angelica Casas
Video journalist, BBC News
BBCCopyright: BBC
The few attendees who gathered at a vigil a few blocks from Robb Elementary didn’t need many reasons to show up - being a part of the Uvalde community was enough of a reason to gather, some said.
Karla Bohman’s voice cracked as she told the group about a family friend whose young daughter, a student at the school, was among those still unaccounted for.
"They don’t know if she’s in surgery or one of the fatalities, but they know she’s a victim of some sort because she’s missing," Bohman cried. "I can’t believe this."
Cheryl Juhasz, a lifelong resident of Uvalde, quietly wept during the prayer.
"You can’t comprehend evil like this. No matter where it happens, but it’s harder when it happens at home."
BBCCopyright: BBC
US vice-president calls for 'sensible' gun policies
ReutersCopyright: Reuters
US Vice-President Kamala Harris called for "reasonable and sensible" policies to ensure other mass shootings don't happen.
Speaking at an event in Washington DC on Tuesday night, Harris said "every time a tragedy like this happens, our hearts break... and yet it keeps happening".
"Enough is enough," she said. "As a nation, we have to have the courage to take action, and understand the nexus between what makes for reasonable and sensible public policy, to ensure something like this never happens again."
President Joe Biden is due to speak on the matter within the next few minutes.
BreakingDeath toll rises to 21
The death toll of the school shooting has risen to 21, according to the US media, citing state police.
Of the 21 victims, 18 are children and three are adults, it said.
State Senator Roland Gutierrez said he was briefed by state police on the fatalities.
'Why are you here?' senator challenges colleagues
Connecticut Senator Chris Murphy, who hails from the state where 26 people were killed in the 2012 attack at Sandy Hook Elementary School, took to the floor of the US Senate on Tuesday to accuse his colleagues of not doing enough to prevent school shootings.
"What are we doing? Why are you here?" the Democrat asked.
"We have another Sandy Hook on our hands," he continued moments after the deaths of 14 students was confirmed in Uvalde.
The attack on Sandy Hook Elementary in 2012 saw 26 people, including 20 children, killed by a lone gunman.
Video content
Video caption: Texas school shooting: 'We have another Sandy Hook on our hands'Texas school shooting: 'We have another Sandy Hook on our hands'
'A nation of anguished screams' - Hillary Clinton
In a tweet reacting to the shooting, former presidential candidate Hillary Clinton said "we are becoming a nation of anguished screams".
She called for gun control: "We simply need legislators willing to stop the scourge of gun violence in America that is murdering our children."
Madison, a 14-year-old Uvalde resident, and her little sister.Image caption: Madison, a 14-year-old Uvalde resident, and her little sister.
It’s a solemn evening here in small-town Texas as dark rain clouds, helicopters and the loss of life loom over Uvalde.
Standing outside her home just down the street from Robb Elementary, Madison, a 14-year-old high school student, can’t believe this happened so close to home.
“I feel bad, they’re babies," she says. "Why them?”
Madison has cousins who were at the primary school and her own high school was forced into lockdown during the shooting.
Police have sealed off the scene, but nearby neighbours stand outside, wondering why it was their town this time.
As officials begin investigations, Uvalde begins to mourn with a vigil underway, just a few blocks from the school.
Shooter suspected of killing his grandmother
The teen is also suspected of killing his grandmother before unleashing the school shooting rampage, three law enforcement sources confirmed to CBS News, the BBC's US partner.
Emergency blood donations
Emergency blood donation appointments are being held on Wednesday following the shooting in Texas.
In a tweet, South Texas Blood & Tissue Center said walk-in and scheduled appointments will be held between 9:00 and 14:00 local time.
It added "our hearts are with the Uvalde community", where the shooting took place.
The suspect was armed with a handgun and an AR-15 semiautomatic rifle, two law enforcement sources have confirmed to the BBC's US partner, CBS News.
He also had high-capacity ammunition magazines when he entered the school, according to the sources.
Texas Senator Ted Cruz rejects gun reform
AFP/Getty ImagesCopyright: AFP/Getty Images
Texas Senator Ted Cruz described the Uvalde shooting as "truly horrific", but said gun reforms were not the way to prevent such crimes.
Speaking to reporters, he said that restricting the rights of "law-abiding citizens... doesn't work. It's not effective. It doesn't prevent crime."
He said "going after felons" is what prevents such crimes and he criticised other politicians for trying to "advance their own political agenda" by calling for gun control.
He added that from past experience, armed law enforcement on campus is the most effective way of keeping children safe.
"We don't know the details of what happened at Robb Elementary School, but there will be a lot of time to examine what steps could have been taken proactively to enhance the safety and security of the school right now," he said.
How many guns are there in the US?
Guns are a highly political issue in the US - pitting gun control advocates against those fiercely protective of their constitutionally-enshrined right to bear arms.
Live Reporting
Edited by Jude Sheerin
All times stated are UK
View more on twitterView more on twitter 
Getty ImagesCopyright: Getty Images Obama wiped away tears in 2012 as he spoke about the children killed at Sandy Hook Elementary SchoolImage caption: Obama wiped away tears in 2012 as he spoke about the children killed at Sandy Hook Elementary School 
Getty ImagesCopyright: Getty Images Biden holds the components of a "ghost gun" at a White House event in AprilImage caption: Biden holds the components of a "ghost gun" at a White House event in April 
ReutersCopyright: Reuters 
ReutersCopyright: Reuters 
BBCCopyright: BBC 
BBCCopyright: BBC 
ReutersCopyright: Reuters Video caption: Texas school shooting: 'We have another Sandy Hook on our hands'Texas school shooting: 'We have another Sandy Hook on our hands' View more on twitterView more on twitter 
BBCCopyright: BBC Madison, a 14-year-old Uvalde resident, and her little sister.Image caption: Madison, a 14-year-old Uvalde resident, and her little sister. View more on twitterView more on twitter 
AFP/Getty ImagesCopyright: AFP/Getty Images 
bCopyright: b
Latest PostWe're ending our live coverage
You can follow all the latest on the Texas school shooting here.
Who was the teacher who died?
Mireles, the teacher who was reportedly killed, was in her early 40s and had a daughter in college, according to her page on the school district’s website.
She had been an educator for 17 years. The page quoted her as saying: "I love running, hiking, and now you just might see me riding a bike!!"
Her aunt, Lydia Martinez Delgado, told the New York Times her niece was “very loved” and "was the fun of the party”.
Adult victim named as fourth grade teacher Eva Mireles
The teacher killed in Tuesday's attack has been named as Eva Mireles according to KSAT-TV, the local ABC News affiliate in the San Antonio area.
The network reports that she worked at Robb Elementary as a fourth grade teacher, instructing pupils between 9-10 years old.
Obama: 'Our country is paralysed'
We have a statement now from former President Barack Obama.
“Across the country, parents are putting their children to bed, reading stories, singing lullabies - and in the back of their minds, they’re worried about what might happen tomorrow after they drop their kids off at school, or take them to a grocery store or any other public space,” he says.
He and his wife Michelle "grieve" for the families, he said, adding: "We’re also angry for them.
"Nearly ten years after Sandy Hook - and ten days after Buffalo - our country is paralysed, not by fear, but by a gun lobby and a political party that have shown no willingness to act in any way that might help prevent these tragedies.”
“It’s long past time for action, any kind of action," says Obama.
In 2015, as he was preparing to leave office, the Democratic president told BBC News that his administration's failure to enact new gun reforms was the greatest frustration of his presidency.
"For us not to be able to resolve that issue has been something that is distressing," he told the BBC's Jon Sopel.
What has Biden done to tackle gun violence?
Biden has previously said he wants to see a ban on assault weapons, high-capacity magazines and mandatory background checks for all gun sales.
But so far he has been unable to persuade Congress to pass "common sense" gun reforms, and has instead focused on executive actions that he can take without congressional approval.
His administration has focused its efforts on the sale of untraceable do-it-yourself "ghost gun" kits.
In April, he signed an order requiring the kits to have serial numbers - legally making them a firearm.
Read more:
Biden sets rule banning sale of untraceable DIY 'ghost gun' kits
'They watched friends die as if they're on a battlefield'
Speaking in the White House Roosevelt Room, President Biden asked Americans to pray for the children of Uvalde tonight.
He began his remarks by praising the "beautiful, innocent" children killed in Uvalde, and their traumautised pupils who watched "friends die as if they're in a battlefield".
"They'll live with it for the rest of their lives," he said.
After his brief remarks concluded, he didn't answer a journalist's question about whether he'll travel to Texas.
It comes just after he went to Buffalo, New York, last week to meet victims and survivors of a shooting at a grocery store in the city.
Biden: 'Why are we willing to live with this carnage?'
"Why are we willing to live with this carnage? Why do we keep letting this happen? Where in God's name is our backbone?" Biden asks.
"It's time to act," he said. "We can do so much more, we have to do more."
Biden: 'When will we stand up to the gun lobby?'
Biden asks: "When in God’s name are we going to stand up to the gun lobby?”
"I am sick and tired of it. We have to act," he said speaking from the White House. "Don't tell me we can't have an impact on this carnage.
"The idea that an 18-year-old kid can walk into a store and buy two assault weapons is just wrong.
"These kinds of mass shootings rarely happen anywhere else in the world."
BreakingBiden on the grief of losing a child
"To lose a child is like having a piece of your soul ripped away," US President Joe Biden said from the White House.
"There's a hollowness in your chest, you feel like you're going to be sucked into it... It's never quite the same."
He was joined by his wife, First Lady Jill Biden, as he spoke.
Uvalde vigil attendees weep and pray
Angelica Casas
Video journalist, BBC News
The few attendees who gathered at a vigil a few blocks from Robb Elementary didn’t need many reasons to show up - being a part of the Uvalde community was enough of a reason to gather, some said.
Karla Bohman’s voice cracked as she told the group about a family friend whose young daughter, a student at the school, was among those still unaccounted for.
"They don’t know if she’s in surgery or one of the fatalities, but they know she’s a victim of some sort because she’s missing," Bohman cried. "I can’t believe this." Cheryl Juhasz, a lifelong resident of Uvalde, quietly wept during the prayer. "You can’t comprehend evil like this. No matter where it happens, but it’s harder when it happens at home."
US vice-president calls for 'sensible' gun policies
US Vice-President Kamala Harris called for "reasonable and sensible" policies to ensure other mass shootings don't happen.
Speaking at an event in Washington DC on Tuesday night, Harris said "every time a tragedy like this happens, our hearts break... and yet it keeps happening".
"Enough is enough," she said. "As a nation, we have to have the courage to take action, and understand the nexus between what makes for reasonable and sensible public policy, to ensure something like this never happens again."
President Joe Biden is due to speak on the matter within the next few minutes.
BreakingDeath toll rises to 21
The death toll of the school shooting has risen to 21, according to the US media, citing state police.
Of the 21 victims, 18 are children and three are adults, it said.
State Senator Roland Gutierrez said he was briefed by state police on the fatalities.
'Why are you here?' senator challenges colleagues
Connecticut Senator Chris Murphy, who hails from the state where 26 people were killed in the 2012 attack at Sandy Hook Elementary School, took to the floor of the US Senate on Tuesday to accuse his colleagues of not doing enough to prevent school shootings.
"What are we doing? Why are you here?" the Democrat asked.
"We have another Sandy Hook on our hands," he continued moments after the deaths of 14 students was confirmed in Uvalde.
The attack on Sandy Hook Elementary in 2012 saw 26 people, including 20 children, killed by a lone gunman.
Video content
'A nation of anguished screams' - Hillary Clinton
In a tweet reacting to the shooting, former presidential candidate Hillary Clinton said "we are becoming a nation of anguished screams".
She called for gun control: "We simply need legislators willing to stop the scourge of gun violence in America that is murdering our children."
Sadness and disbelief as night falls in Uvalde
Angelica Casas
Video journalist, BBC News
It’s a solemn evening here in small-town Texas as dark rain clouds, helicopters and the loss of life loom over Uvalde.
Standing outside her home just down the street from Robb Elementary, Madison, a 14-year-old high school student, can’t believe this happened so close to home.
“I feel bad, they’re babies," she says. "Why them?”
Madison has cousins who were at the primary school and her own high school was forced into lockdown during the shooting.
Police have sealed off the scene, but nearby neighbours stand outside, wondering why it was their town this time.
As officials begin investigations, Uvalde begins to mourn with a vigil underway, just a few blocks from the school.
Shooter suspected of killing his grandmother
The teen is also suspected of killing his grandmother before unleashing the school shooting rampage, three law enforcement sources confirmed to CBS News, the BBC's US partner.
Emergency blood donations
Emergency blood donation appointments are being held on Wednesday following the shooting in Texas.
In a tweet, South Texas Blood & Tissue Center said walk-in and scheduled appointments will be held between 9:00 and 14:00 local time.
It added "our hearts are with the Uvalde community", where the shooting took place.
BreakingSuspect had AR-15
The suspect was armed with a handgun and an AR-15 semiautomatic rifle, two law enforcement sources have confirmed to the BBC's US partner, CBS News.
He also had high-capacity ammunition magazines when he entered the school, according to the sources.
Texas Senator Ted Cruz rejects gun reform
Texas Senator Ted Cruz described the Uvalde shooting as "truly horrific", but said gun reforms were not the way to prevent such crimes.
Speaking to reporters, he said that restricting the rights of "law-abiding citizens... doesn't work. It's not effective. It doesn't prevent crime."
He said "going after felons" is what prevents such crimes and he criticised other politicians for trying to "advance their own political agenda" by calling for gun control.
He added that from past experience, armed law enforcement on campus is the most effective way of keeping children safe.
"We don't know the details of what happened at Robb Elementary School, but there will be a lot of time to examine what steps could have been taken proactively to enhance the safety and security of the school right now," he said.
How many guns are there in the US?
Guns are a highly political issue in the US - pitting gun control advocates against those fiercely protective of their constitutionally-enshrined right to bear arms.
Here's what we know about America's gun culture and the impact it has - in seven charts.