An explosion at an ammunition and explosives factory in north-west Turkey has killed at least 12 people and injured four others.

The blast happened at 08:25 local time (05:25 GMT) in the capsule production section, the governor of the city of Balikesir, Ismail Ustaoglu, said.

Interior Minister Ali Yerlikaya said the cause was not yet clear, but that authorities had ruled out sabotage.

Videos from the scene showed a fireball erupt from the factory, destroying part of the building, followed by plumes of dark smoke.