Bulgaria explosives factory blast kills 15

A blast at an explosives factory north of the Bulgarian capital Sofia has killed 15 people, prompting the government to declare Friday a day of national mourning.

Thirteen men and two women were killed, and three other women employees hurt, at the factory near Gorni Lom.

"The blast was so powerful that it left craters," civil defence force director Nikolay Nikolov said.

He said the cause of the explosion was probably "human error".

With the country holding a general election on Sunday, one leading politician said his party was muting its campaign as a sign of respect.

Former Prime Minister Boiko Borisov, whose Gerb party is tipped to win against the outgoing Socialists, told Bulgarian TV station 24 Hours that concerts and other events would be called off.

The explosion occurred at around 17:00 (14:00 GMT) on Wednesday with a big secondary blast reported at 21:45.

The factory, some 120km (75 miles) north of Sofia, destroys stockpiles of obsolete munitions for the Bulgarian army and Dnes daily newspaper quoted an expert as saying it had been handling explosives from Greece.

Some 10 tonnes of highly explosive chemicals were being stored at the plant.

"The factory has been reduced to ashes," an interior ministry spokesman said.

There were explosions at the factory in 2007 and 2010, in which several people were hurt.

Two units of the plant were flattened in the 2010 blast.