A Bangkok residence building collapsed on Saturday, killing at least four rescue workers and a resident, according to an emergency worker.

The three-story house, located in a luxury gated community in western Bangkok, was engulfed in flames around 6 am and the fire raged for about an hour before it was put out.

At around 7 am, as firefighters and rescue workers were moving through the razed structure in the Thai capital, it abruptly collapsed, killing at least five, including a resident.

"The cause of the collapse remains unknown. The fire could be the main reason for interiors of the residence building to collapse," Jiratthikorn Banjongkit, chief of rescue at the Poh Teck Tung Foundation, told AFP.

By 4 pm, he said that rescue workers and firefighters were still working to free four of the bodies -- only one had been retrieved from under the rubble of concrete and wiring structure.

AFP-verified footage showed firefighters standing by the building and hosing down its charred exterior, with at least one person on the second floor, when the building abruptly crumbled.

Bangkok governor Aswin Kwanmuang told reporters that there was "no safe passage" to easily retrieve the bodies and see if more had been trapped.  

"We will have to gradually drill and use small-sized equipment as larger equipment could cause (the debris) to collapse further."

Aswin added that a forensic team was investigating the cause of the fire.

Building collapses are rare in the metropolis of Bangkok, which is replete with gleaming towering malls and residential sprawl.