ATLANTA (AP) — A fierce fire roared through a boarding house in Atlanta early Monday, collapsing the house in on itself and killing six people, authorities said.

The victims included four men and two women, Atlanta Fire Rescue spokesman Cortez Stafford said. Their names were not immediately available. Stafford the cause of the fire had not yet been determined.

Fire crews were called to the house on the city's northwest side about 5 a.m. Monday. When they arrived, the blaze had already spread through the roof and throughout the building, making it impossible for firefighters to reach some areas of the home, Stafford said.

"We got on scene and did the best job we could to try to get inside — there was just too much fire," he told reporters at the scene. He said the single-level structure with a basement had "collapsed in on itself."

Fire crews raced to the rear of the home to try to get in but discovered there was no exit there, Stafford told WXIA-TV.

Five of the victims were found in the rear of the home and one was found in a front bedroom, he said.

There were two space heaters in the home, which always ran because it was cold in the house, said Jannett Ragland, who said she was at the home in the early morning hours before the fire. One space heater was in the front of the house, and one was in the back, she said.

The owner of the home allowed people to stay there when they needed to, said Kimberly Wise, a neighbor.

With the six deaths, there have now been a total of 39 fire deaths in Georgia this year, said Glenn Allen, a spokesman for the state fire marshal.