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.

Further footage from the aftermath shows mangled parts of steel littering the surrounding area.

The explosion caused tremors throughout the Köteyli township, witnesses told CNN Turk.

Many fire crews were sent to deal with the blaze and health and security units were dispatched to the area, officials said.

"I wish God's mercy upon our deceased citizens and a speedy recovery to our injured," Mr Ustaoglu said in a post on social media

An investigation has been launched into the circumstances that led to the blast, Justice Minister Yilmaz Tunc said.