Thai indie band Thotsakan was performing at a packed bar in Bangkok on Sunday when band manager Ice Athipat Wijarn, seated off stage, saw smoke emerging from behind the keyboardist.

The keyboardist, Kwang, shouted for people to flee - and within seconds a fierce blaze tore through Rong Beer Na Lat Phrao, in the city's vibrant Chatuchak district.

Ice recalls fumbling with the door in the smoke-engulfed room as he tried to escape. Then something exploded, throwing him out of the bar.

The blaze killed at least 27 people and left dozens more injured, authorities confirmed on Monday.

Kwang, along with Thotsakan's female singer Breeze and drummer Bew, died after succumbing to their injuries, according to a Facebook post from another band member, Patchara Songphatkaew.

The whereabouts of Din, a male singer, is still unclear.

"Maybe a miracle will happen," Patchara wrote. "Let's pray things turn out well."

Thotsakan's lead singer Tik Chaichana managed to escape unscathed only because he went to the washroom moments before the fire broke out, Thai media reported. Videos online showed him sobbing as he ran out of the burning bar.

"I'm safe, thank you everyone for your concern. But my phone and all my belongings burned... My mind is truly not okay right now," Tik wrote in a Facebook post.

Rong Beer Na Lat Phrao, like many bars and pubs along the same street, was popular with locals. At the time of writing only one foreigner, a Laotian, has been identified among those who died.

Footage posted online showed panicked customers screaming as they fled – some with their clothes on fire – through the flaming front door. More than 60 people are now being treated in hospital, eight of whom are critically injured, Thai authorities say.

Several residents in the area described being stunned by the scale of the blaze.

"I saw [firefighters] trying to extinguish the flames almost everywhere," said Titi Liewcha, who lives across the street from the bar. "I saw ambulances and rescue vehicles everywhere. I didn't know what to do. I just sat there stunned for a while."

Titi and Sirinya, who also lives nearby, told BBC Thai they initially feared that the fire would spread towards their homes.

"This is the first time I've seen such a major fire," Sirinya said.

Upon arriving at the scene, firefighters were able to bring the flames under control in about half an hour. Despite their efforts, nine men and 18 women were killed.

Sirinya is worried that such a tragedy could recur "because there are so many of these pubs".

She's visited the bar once before, and recalls it being "very dark, with a low ceiling".

"The fire escape routes are not clear," she added.

Phatsara Khamloet, who visited the pub in May, was also struck by the dark and "maze-like" interior.

"It looked like it wasn't even open because of the glass. It was so dark you couldn't see anything inside," Phatsara said.

She recounted having to navigate a "winding route" to reach the washroom, and noted that the exits were not well marked.

"The moment I stepped in, my first feeling was, 'Whoa, if there's a fire, how would we even get out?'"

Earlier on Monday, Bangkok governor Chatchart Sittipunt said the flammable interior decorations on the bar's ceiling may have facilitated the blaze's rapid spread.

There were also reports of people found unconscious near the building's emergency exit, suggesting that there may have been some obstruction, Chatchart added. He acknowledged, however, that a thorough investigation was needed to confirm such details.

The tragic blaze has reinforced calls for authorities to strengthen fire safety standards and for proper training for staff, especially those in the nightlife industry.

A driver who works close to the bar suggests that venue owners should hold regular fire drills to familiarise employees with evacuation procedures.

"Or when it comes to designing a place like this, the doors should be designed with more width in mind. Make them wider, make it easier for customers to escape," he says.

"I feel sorry for the people who died. I feel sorry for them because they probably had no idea what was happening."