Pakistani city of Quetta in shock after double attack

A day of official mourning has been declared in the Pakistani city of Quetta after 25 people were killed by militants in twin attacks on Saturday.

After a bomb on a bus killed 14 female students and injured 22, gunmen attacked a hospital treating survivors, where they killed another 11 people.

Four attackers were also killed and one arrested, officials say.

No clear motive for the attack has yet been established but a Sunni Muslim militant group is being blamed.

A man purporting to be a spokesman for Lashkar-e-Jhangvi told the BBC the attacks were revenge for an earlier raid by security forces against the group, in which a woman and children were killed.

Quetta, a city of 900,000 people in the south-west of the country, has long been troubled by violence mainly targeting the Shia Muslim minority.

The city is reeling from a deep sense of shock, trying to make sense of Saturday's events, the BBC's Shahzeb Jillani reports.

Funerals are being planned for the victims of the attack while an official day of mourning is being observed across the province of Balochistan, of which Quetta is the capital.

Saturday's bloodshed began when a bomb exploded on a bus carrying students at Sardar Bahadur Khan Women's University.

When survivors were brought to a medical centre, suspected suicide bombers stormed the building and started shooting indiscriminately.

A five-hour stand-off between the militants and security forces left nurses, security personnel and a senior city official dead.

UN Secretary General Ban Ki-moon condemned the attacks in a statement, saying no cause could justify such violence.

"The secretary general notes with dismay that violence against women and educators has increased in recent years, the aim being to keep girls from attaining the basic right to education," his spokesperson said.

Groups like Lashkar-e-Jhangvi have carried out major bombings against Shia religious minorities, our correspondent says.

The group is known for close ties with the Taliban and al-Qaeda.