A number of the victims were found near a fire exit that authorities believe may have been blocked, the governor said.
Motorbike taxi driver Surin Jaiharn said he saw the fire burst into the street from the bar door and helped about five people fleeing with burnt and blistering skin.
“I feel depressed. I saw many deaths and I do not know the fate of the people I helped,” the 45-year-old said.
He said he used cloths to put out flames on their bodies while another driver carried a female victim away from the danger.
Authorities said on Monday they had identified 10 of the victims so far, nine of them Thai nationals and the other from Laos.
‘Blind spots’
The venue has a stage, two bars and a kitchen, with a total capacity of more than 300 people, as well as four fire exits, according to a Facebook post promoting a live show this month.
Prime Minister Anutin Charnvirakul, who earlier visited the scene, said the venue was licensed to operate as a restaurant, adding that police were looking at its inspection record.
He assured the victims and their families they would “receive the best possible care”.
Initial inquiries suggested there were “blind spots” without a visible fire escape route, Anutin told reporters at City Hall.

He urged everyone to wait for the investigators’ report, but added, “There will be no leniency if any laws have been broken.”
The fire broke out around 11:00 pm on Sunday and police said that by around 2:00 am on Monday it was under control.
Laotian tourist Kan Kutirat told AFP he “heard loud screaming from a lot of people inside, chaos happened”.
“I never experienced anything like this before,” he said. “The images are still stuck in my mind.”
‘Blocking the way’
Most of the bar’s windows were blown out and AFP reporters saw beer bottles and stools covered in white dust.
Earlier, Anutin said musicians at the venue described “smoke from a circuit breaker near the stage followed by the power going out and an explosion.”
“Most of the victims ran to the back, to toilets with no exit. It could be because of panic because there was fire and smoke,” the premier told reporters.
Suriyachai Rawiwan, head of Bangkok’s disaster prevention department, said emergency services arrived within five minutes of being called but the fire had already spread.

“When we went in to search, we found tables and seating blocking the way everywhere and the heat was intense,” Suriyachai said.
Thailand’s approach to health and safety regulations, particularly in its bars and nightclubs, has long raised concerns.
Most recently, 25 people died after a fire ripped through the Mountain B nightclub in Thailand’s eastern Chonburi province in 2022.