July 12 (UPI) — An intense fire that ripped through a Bangkok pub early Monday killed at least 27 people and injured nearly 20 others, officials said as an investigation was launched into the cause of the blaze.

Authorities received a report of the fire at the Rong Beer Na Lat Phrao pub in Bangkok’s densely populated Chatuchak district at 12:02 a.m. local time, Thailand’s Department of Disaster Prevention and Mitigation said in a statement.

“The fire was burning intensely,” according to the department, which said responders from various agencies worked to extinguish the blaze and rescue the injured and people trapped inside.

Videos of the bar’s entrance posted online show people screaming and running out of the establishment followed by flames erupting from the door.

Officials said the fire was brought under control by 12:32 a.m.

Images of the aftermath posted online by the Department of Disaster Prevention and Mitigation show the charred remains of the bar’s interior.

A preliminary inspection of the scene found that 27 people had been killed, the department said. The identities have not been released, but the department said 18 were women and nine were men.

Of the 18 people injured, eight were listed as red cases, meaning they were either in critical or life-threatening condition, seven were labeled yellow for serious but stable condition and three were considered green cases with minor injuries, the department said in an update.

“Forensic investigators are examining the scene to determine the cause of the fire,” the Department of Disaster Prevention and Mitigation said.

Prime Minister Anutin Charnvirakul arrived at the scene at about 1:30 a.m. and was joined by Disaster Prevention and Mitigation Director-General Teerapat Katchamat and Bangkok Gov. Chadchart Sittipunt.

Anutin told reporters at the scene that most fatalities were the result of smoke inhalation. He said that he was told by witnesses that the fire appeared to have started near a circuit breaker on the restaurant’s stage before the facility was plunged into darkness, the Bangkok Post reported.