At least three gendarmerie personnel were killed in the blast that occurred as explosives and fireworks from a previous blast site were being transferred for disposal.
A truck carrying fireworks exploded in northwestern Turkey, killing three gendarmerie officers and wounding 12 others.
The fireworks and explosives, which were from a factory where a blast last week killed seven people, were being transported to be destroyed in a controlled explosion in Sakarya, the Interior Ministry said on Thursday in a statement. The material exploded as it was being taken off the truck at a quarry, and two of the dead were from the bomb disposal unit of the gendarmerie, the ministry said.
Interior Minister Suleyman Soylu told journalists at the scene that the truck driver was in critical condition and 11 military police officers were wounded.
He said 15 tonnes of explosives had already been disposed of and the explosion took place when an estimated 1.5 tons remained. The explosion would be investigated, Soylu said.
Television footage showed a destroyed truck in a blackened pit, fire trucks and ambulances.
The remaining explosives at the factory were ordered by the prosecutor's office to be destroyed in a controlled detonation at a stone pit in Taskisigi of Adapazari district, Sakarya Governor Cetin Oktay Kaldirim said.
Thursday's blast occurred in the mountainous area while the materials were still on the truck, the governor added.
Following the incident, Turkey's Interior Ministry said two out of the three gendarmerie forces personnel who were killed belonged to the disposal team.
The cause of the July 3 explosion at the factory, which is away from residential areas, was under investigation.
A factory owner and four employees were arrested.