The massive explosion at the foam and plastic pellet manufacturing factory which is located just near Suvarnabhumi Airport killed one rescue worker and injured 29 people, while prompting the evacuation of a wide area.

Rising smoke is seen behind the giant Buddha statue in Samut Prakan province, Thailand, Monday, July 5, 2021.
Rising smoke is seen behind the giant Buddha statue in Samut Prakan province, Thailand, Monday, July 5, 2021. (AP)

Thousands of people on the outskirts of Thailand's capital have been evacuated and firefighters battled blazes for hours after a factory explosion that killed one rescue worker and wounded 29 people.

The fire broke out at around 3 am local time on Monday at a foam and plastic pellet manufacturing factory just outside Bangkok near Suvarnabhumi Airport, blowing out windows of surrounding homes and sending debris raining from the air.

Residents in Samut Prakan province who live within a five-kilometre (3.1-mile) radius of the factory were being moved away as precaution, authorities said.

Local disaster authorities said 70 houses were damaged and fires were still being fought nine hours after the explosion in the early hours of Monday.

The cause of the blast had yet to be determined.

"At first it felt like lightning. After that, I heard something drop loudly, and for a while the house started shaking like there was an earthquake," said Baitong Nisarat, a resident.

Hazardous chemical

Firefighters used helicopters to dump water on hard-to-access areas in the large complex. By mid-morning the main blaze at the Ming Dih Chemical factory had been brought under control, but a massive tank containing the chemical styrene monomer continued to burn, said local disaster prevention official Chailit Suwannakitpong.

Styrene monomer, a hazardous liquid chemical used in the production of disposable foam plates, cups and other products, can produce poisonous fumes when ignited.

The chemical itself also emits styrene gas, a neurotoxin, which can immobilize people within minutes of inhalation and can be fatal at high concentrations. Last year in the Indian city of Visakhapatnam, a leak of styrene gas from a chemical factory killed 12 people and sickened more than 1,000.

The airport said flights and its operations were not impacted by the blast.