Three foreigners were killed after a fire broke out at a hotel near Bangkok's popular backpacker district on Sunday night, authorities said, with seven others being treated in hospital.

A fire broke out on the fifth floor of the six-storey Ember Hotel, Bangkok's Fire and Rescue Department said, with a woman dying on the scene and two men pronounced dead at the hospital.

Authorities were still determining the nationalities of the deceased.

The hotel is near the Khao San area of Bangkok that is popular with backpackers and known for its bars and hostels.

"Authorities reacted quickly and the fire alarm sounded, but the smoke was fast," Bangkok Governor Chadchart Sittipunt told reporters on Monday.

There were 75 people in the hostel, 34 of whom were rescued from the rooftop, he said.

The cause of the fire was still being investigated, the governor added. He has ordered a city-wide inspection of fire escape routes in hotels and entertainment venues.

"We have to build confidence and take care of tourists," Chadchart said.

Tourism is a key driver of Southeast Asia's second-largest economy. Thailand recorded 32 million foreign tourist arrivals from Jan. 1 to Dec. 1, up 28% from a year earlier, and they spent 1.5 trillion baht ($43.6 billion).

In 2019, before the pandemic, visitor numbers reached a record of nearly 40 million.