An explosion at a fireworks factory in central Thailand’s Supanburi province has killed at least 18 people, rescue workers said today.

“We confirm 18 deaths,” a member of the rescue team at the scene told AFP. The explosion happened in the afternoon (local time), according to Thai media.

In images released by rescuers, the factory appears to have been leveled by the explosion and only some ruins remain.

The police confirmed to AFP that there were many deaths without being able to give an exact count of the time or the cause of the explosion. Reuters reports that the preliminary investigation, according to the police announcement, speaks of 20 dead and many injured.

“We cannot say if all the workers were killed. Officials enter the premises to investigate. They have not found any survivors,” provincial governor Natapat Suvanpratep told Reuters.

Prime Minister Shreta Thavisin was informed of the explosion while at the World Economic Forum in Davos, Switzerland, and called for an immediate investigation.

“The prime minister ordered an inspection of the factory to see if it was operating legally and if the explosion was a result of negligence. The law must be implemented to the fullest because there are innocent deaths and injuries,” Shreta’s office said.