A deadly blaze swept through a bar in Bangkok, Thailand, late on Sunday, leaving at least 28 people dead and dozens more critically injured, the authorities have reported.

According to eyewitness accounts the fire originated near the bar’s music stage and quickly spread, with many customers getting lost in the smoke and becoming trapped in the bathrooms in the ensuing panic.

At least 71 people were injured, with 25 remaining in critical condition, the Bangkok Metropolitan Administration reported on Monday.

“When the power went out – for instance, at the restroom entrance – visibility dropped to zero. Everyone tried to exit, but the restroom had no windows; it was a dead end,” Thai national police chief Kittharath Punpetch said in a press briefing on Monday.

“Once inside, escape was impossible because smoke had already filled the area, and facing it meant confronting the danger.”

Thai police have begun focusing their forensic investigation on the area above the venue’s music stage as they work to determine what caused the deadly fire, he added.

The police will investigate the owners for negligence amid reports that the emergency exits were blocked, he said.

Terrifying video from the night of the incident shows a plume of fire shooting out of the bar’s front entrance, as customers run out surrounded by the flames.

Harrowing footage from inside the bar shows people choking on smoke as they run out of the darkened venue.

The Chatuchak District Office has issued an order closing the establishment for 30 days while the investigation takes place.