A fire engulfed an oil and farm supply shop after a transformer explosion in eastern Thailand.

The blaze broke out when the blast ignited fuel inside the building along Sukhumvit Road in Rayong on the morning of October 3.

Footage shows thick black smoke billowing out of SYK Machinery as firefighters battled the raging flames at around 7:45 am local time.

The fire spread quickly after ripping through a storage area filled with thousands of litres of fuel.

More than 100 firefighters sprayed water to contain the inferno and prevent it from reaching a nearby petrol station, which holds a 4,500-litre underground fuel tank.

Authorities said the fire was brought under control at 11 am. One injured officer was rushed to Rayong Hospital for treatment.

A security guard across the shop said he saw the transformer explode before the sparks flew into the shop, setting it ablaze.

Rayong City Mayor Wichit Srichala said: 'We deployed over 10 fire trucks to contain the blaze and requested fire trucks from IRPC for assistance. The cause of the fire is suspected to be an electrical short circuit.'

In a press conference, Deputy Rayong Governor Kanchai Thepworachai said the firefighters remained at the scene to prevent reignition.

He said: 'The three-storey building was sealed off due to the risk of collapse, until the Rayong Public Works and Town Planning Office clears it for safety. The cause of the fire and the damage caused have not yet been determined. Forensic police from the Rayong Provincial Police will conduct an investigation.'

Fires in Thailand are commonly caused by aging electrical infrastructure, extensive use of wood in construction, and regional heatwaves that can exacerbate fire risks.

Rapid fire response can also be hampered in densely packed neighbourhoods where narrow streets can delay firefighting efforts.