The security official said the explosion came as dozens of residents were inside the factory searching for ammunition, a day after a raid by suspected Al-Qaeda fighters. The cause of the explosion remained unclear.

Around 30 armed and hooded gunmen looted the factory on Sunday and made off in four vehicles with cases of weapons, witnesses said.

The incident came as a security official said that suspected Al-Qaeda militants had seized control of Jaar, a town in the restive southern province of Abyan. Source