At least 27 people have been killed and eight left critically injured after a fire tore through a bar in Bangkok's popular Chatuchak district.

Firefighters were called to the scene just after midnight on Monday and discovered patrons fleeing through the venue's flame-enveloped front door.

Eyewitnesses say the fire started near the bar's stage and spread rapidly. Footage posted on X shows flames blasting from the bar as people run out, some screaming and falling over.

This is not the first time such incidents have occurred in Thailand. Despite official promises to improve fire and electrical safety standards following previous accidents, they are still often poorly enforced.

Firefighters arrived at the scene just after midnight, reportedly after a passing driver saw the venue on fire around 23:30 local time. He told local news outlet the Daily News that he leapt out of his car and broke windows to help two people escape.

The official cause of the fire is still under investigation, said Prime Minister Anutin Charnvirakul.

He also told reporters that he had spoken to a musician, who was performing when the fire started, who recounted what happened.

"He said that there was a fire at the cut-out switch, and after that things happened very quickly. There was blasting and everybody tried to flee from the smoke and flames," he said.

"Many of them were not able to make their way out because they went to the back of the building and tried to hide themselves from the smoke and flames in the toilet, and that's where we found most of the bodies."

Firefighters were reportedly able to bring the flames under control in about half an hour, but despite this - some nine men and 18 women were killed, and more than 60 are being treated in hospital, eight of whom are critically injured.

Initial findings suggest that majority of the victims had died from smoke inhalation, said Suriyachai Raviwan, the director of Bangkok's disaster department. However, he added, further investigation was needed to confirm this.

One motorcyclist, Surin Jaiharn, told AFP that he helped about five people flee the burning bar, using clothing to extinguish flames on their bodies.

"I feel depressed. I saw many deaths and I do not know the fate of the people I helped," he told AFP.

As of Monday morning, the bar - Rong Beer Na Lat Phrao - has been cordoned off, with shattered windows and furniture piled up outside its entrance. An acrid smell of burning lingers in the air.

Confronting pictures taken after the fire had been brought under control show many body bags lined up outside the bar, and a large cordon around the area.

Inside, the furniture, walls and ceiling are completely blackened, and parts of the ceiling is peeling off.

Bangkok governor Chatchart Sittipunt visited the scene and claimed the fire had spread quickly through the flammable interior decorations on the bar's ceiling. Toxic smoke from the burning decorations might have also caused victims to lose consciousness, he added.

There were also reports of numerous people found unconscious near the building's emergency exit, said Chatchart, who added that there might have been tables or other objects obstructing the area.

"However, this matter requires a thorough and official investigation by forensic officers," he added.

This is not the first time such an incident has occurred.

Four years ago another fire in a bar in a town south of Bangkok killed 22 people; in 2009, 66 people died in a nightclub fire in the capital.