Update: Fairfax County Fire and Rescue officials said a faulty recessed light on the top floor of a townhouse at 1605 Apricot Ct. was the cause of a fire early  Tuesday.
Damage has been estimated at $150,000.
Two residents escaped unharmed after a neighbor smelled smoke, called 911 and alerted the residents to the fire, fire officials said.
Original story, Tuesday 9 a.m.:
Two residents escaped from their burning townhouse early Tuesday after a neighbor pounded on the front door to alert them of the blaze, Fairfax County Fire and Rescue officials said.
FCPD received the call to the fire at 1605 Apricot Ct. about 4:20 a.m., said fire rescue spokesman Dan Schmidt.
Schmidt said the end unit home had smoke alarms but the alarms did not go off. A neighbor called 911 and went to the house to tell the residents to get out.
When firefighters arrived, the rear of the house and the roof were fully involved, Schmidt said. Damage also extended into an adjacent townhouse. It took firefighters about 30 minutes to get the fire under control.
The residents have been displaced but were unharmed. Investigators do not yet have an cause of the fire or a damage estimate.