BANGKOK, Thailand - Twenty-three people have died after an explosion at a fireworks factory in central Thailand on Wednesday, the provincial governor said.

Images shared by the local rescue service showed metal debris littered on the ground, and a huge plume of black smoke.

The blast occurred at around 3:00 pm (0800 GMT) near Sala Khao township, in central Suphan Buri province.

"We received reports from EOD team that there were 23 confirmed dead," Nattapat Suwanprateep, Suphan Buri province governor, told AFP, referencing the Explosive Ordinance Disposal group.

There was no indication of what may have caused the explosion.

However, Nattapat said officials were investigating what may have triggered the incident.

"The factory was operating legally with valid licences," he said.

Police officers said the surrounding area had not been damaged.

"Glass windows on one house have been affected by the explosion but no other reports," Nattapat said.

Police Lieutenant General Naiyawat Phademchid told AFP Prime Minister Srettha Thavisin -- currently in Switzerland for the World Economic Forum -- had been informed of the incident.

"Estimate of 20 deaths, however, we cannot confirm the official death toll," said the police officer, who is responsible for lower western Thailand.

He said that officials were sealing the surrounding area, and would begin to identify the bodies once the situation had stabilised, without going into further details.

"There were on average about 20 to 30 people working at this factory every day," he said.

In an official statement posted online, Prime Minister Srettha expressed his sorrow for the families of those killed.

Srettha also ordered an investigation into whether the workshop was operating illegally, as well as the cause of the incident.

- Accidents common -

Explosions at workshops producing firecrackers and other pyrotechnics are not uncommon in Thailand.

At least 10 people died after an explosion in a fireworks warehouse in Sungai Kolok town in southern Narathiwat province last year.

The blast was believed to have been caused by welding during construction work on the building, and police later sought the owners on charges of negligence.

Last year 11 people were also injured when a fireworks factory exploded in the northern city of Chiang Mai.

The Southeast Asian kingdom also has a poor safety record in the construction sector and deadly accidents are common.