A woman in the Sudley area saw a glow at the rear of her home early Thursday as she returned to bed after being awake for some time.
She went to investigate, found a fire burning on her rear deck and called 911, said Matt Smolsky, Prince William Fire and Rescue spokesman.
The woman managed to wake the other eight people who lived in the house and everyone escaped unharmed, Smolsky said.
Firefighters arrived at the house at 9906 King George Drive at 5:01 a.m. and found heavy smoke coming from the rear of the house, Smolsky said.
Investigators have not yet determined how the fire that caused $150,000 started, but were able to determine it started on the deck, Smolsky said.
The Prince William Chapter of the American Red Cross helped the family find shelter, Smolsky said.