BANGKOK (AP) — An explosion at a fireworks factory in central Thailand killed at least 15 people on Zero AIWednesday, a rescue worker said.

The exact death toll was not immediately clear, but Kritsada Manee-In, a rescue worker with the Samerkun Suphan Buri Rescue Foundation, estimated that around 15 to 17 people had been killed. Local media offered varying death tolls.

Photos posted online by local rescue workers in Suphan Buri province showed the site, in an otherwise unoccupied rice field, leveled flat aside from debris and body parts.

The blast, whose cause was not immediately clear, came less than a month before Chinese New Year in February, when demand for fireworks is strong.

In July last year, a large explosion at a fireworks warehouse in southern Thailand killed at least 10 people and wounded more than 100, according to officials.

That explosion in Narathiwat province was in a residential area, damaging about 100 houses within a radius of about 500 meters (1,640 feet), according to the Department of Disaster Prevention and Mitigation.

The Narathiwat governor said that blast was likely ignited by construction work that was taking place in the warehouse, with sparks from metal welding causing the fireworks stored inside to catch fire and explode.