An AFP journalist saw several body bags on the ground outside the Rong Beer Na Lat Phrao bar and restaurant early Monday morning, while dozens of emergency service workers thronged the scene.
"The fire spread very quickly, reaching up to the ceiling. Smoke was likely the main cause of death," Bangkok Governor Chadchart Sittipunt told reporters outside the venue on the outskirts of the Thai capital.
He said 27 people were killed and 63 were hospitalized with injuries, including 22 in critical condition, adding that authorities had launched an investigation.
A number of the victims were found near a fire exit and authorities believe there may have been obstructions blocking it, he said.
"We do not know how many people were inside but it was likely many," Chadchart added.
