Three people were killed when a fireworks-laden truck exploded in Turkey on Thursday -- the second such incident in less than a week, officials said.

The vehicle was carrying unexploded materials from a fireworks factory in the Black Sea province of Sakarya that was itself hit by a blast on Friday, killing six people and injuring over 100. Television images showed white smoke rising from the scene of the latest incident in a mountainous area of the Adapazari district in Sakarya.

The interior ministry said three gendarmes were killed and six hurt in the blast which occurred as fireworks were being transferred ahead of a controlled detonation, the official Anadolu news agency reported. Two of the dead were from the team in charge of disposing of the unexploded fireworks in a quarry. 

Interior Minister Suleyman Soylu travelled to the scene, Anadolu reported. Turkish officials launched an investigation into last Friday's incident, which was described by the government's disaster agency AFAD as an "industrial accident".

Local media reported that two owners of the factory were detained this week. The HaberTurk broadcaster's website had reported that there had been previous explosions at the factory in 2009, 2011 and 2014, one of them fatal.