Authorities estimate that the fireworks factory in Suphan Buri may have had at least 500 kilogrammes of explosive materials stored in its compound before the blast on Wednesday afternoon.
The explosion occurred at village Moo 3 in tambon Salakhao of Muang district at about 3.30pm, killing 23 workers instantly. The explosion also caused damage to four houses located about 300 metres from the factory.
The force of the blast spread debris in a radius of 100m, with human remains scattered everywhere.
Pol Maj Gen Kamthorn Auichareon, commander of the Police Scientific Crime Detection Centre in Nakhon Pathom, on Friday told the media that the incident probably occurred where workers produced and packaged fireworks as 22 explosion craters were spotted in the area.
A spark might have occurred in a warehouse area where the factory stored gunpowder, sulphur and other chemicals because police found a large crater, about 5m wide, 5.3m long and 1m deep.
Evaluating the size of the large crater, an investigation concluded that the factory had kept about 500kg of explosive materials and that explained the blast in a radius of about 1.5km, Pol Maj Gen Kamthorn said.
An in-depth investigation is underway to establish the exact cause of the explosion, he said.
The police said the incident was not the first. In November 2022, the factory partly exploded. One worker was killed in a fire that followed the blast, and three others were seriously injured. The incident forced the factory to close temporarily before it later reopened.
Residents told the media that in 2021, most villagers voted in favour of the owner of the factory starting the business during a public hearing as they lived far away from the plant and their family members, mostly farmers, could earn more by working there.
A source from the Ministry of Industry discovered that its facilities had never undergone an inspection despite needing a yearly licence to operate.
Minister of Social Development and Human Security Varawut Silpa-archa, meanwhile, revealed there were 23 confirmed dead from 17 families.
The Banharn-Jamsai Silpa-archa Foundation will fully cover the tuition of the children whose parents were killed in the incident until they graduate from university. The children's ages range from eight to 18 years old.
The ministry will provide compensation for house repairs and arrange a psychiatric team to take care of the mental health of the families of the dead.
Anukul Peedkaew, permanent secretary for social development, said the ministry has set up a war room to assist everyone affected by the incident.
For seven days, social workers will closely monitor the families of those killed. The ministry will work with the Public Health Ministry for mental treatments.
The ministry will appraise the damages to learn what people need for assistance. For its long-term plan, it will spruce up the living environment and offer occupational training.
Prime Minister Srettha Thavisin said he would look into legal matters to see how to rectify the law to place small-sized fireworks producers under the control of the Industry Ministry with the same safety regulations.