UPDATE: One rescuer was killed and more than 60 people injured in an overnight explosion and fire at a chemical factory that continued to send black smoke into the sky in Samut Prakan late into Monday afternoon.

Rescue foundations reported one of their firefighters was killed by the fire and 12 others were injured. Fifty other people were also hurt.

The explosion occurred about 2.50am at the Taiwanese-owned Ming Dih Chemical Co factory which produces plastic foam.

There were five or six warehouses in the factory compound, where 50 tonnes of chemicals were stored.

The explosion was followed by a massive fire which engulfed the entire factory and caused extensive damage to buildings and houses within in a one-kilometre radius.

More than 30 fire engines rushed to the scene.

The fire was initially believed to have been brought under control around dawn, but smoke continued to rise above the gutted ruins.

Authorities ordered the urgent evacuation of all people within a five-kilometre radius. There were worries there could be more explosions as the fire was moving towards another area used to store chemicals.

Helicopters were sent to dump water on the fire, as thick smoke continued to billow from the burning factory. The smoke plume was clearly seen in Bangkok and was also visible from Suvarnabhumi airport, but flights were not affected.

The explosion was felt as far as nine kilometres from the factory site.

"I heard a big bang. It sounded very close and I thought it was a huge lightning bolt," said Aree Thongboonrawd, a Bangkok Post employee whose house is nine kilometres away.

Owners of houses damaged by the explosion and fire were advised to register a complaint with police.

The cause of the explosion was unknown.