A propane grill on a deck caught fire, damaging two townhouses, Prince William County authorities said.
Fire crews responded to the 9600 block of Bedder Stone Place in Bristow about 7 p.m. Monday, officials said. The homeowner preheated the grill and left it unattended. Neighbors then alerted the homeowner that the deck was on fire.
The propane tanks' relief valve opened, causing the fire to grow rapidly. Crews put out the blaze after it extended to the next home.
The fire marshal's office said damage is estimated at $300,000.
Fire officials strongly discourage grills on decks. They say grills should be at least 15 feet away from any structure.
No one was injured in the fire.