Units responded to a house at 11153 Lake Chapel Lane about 4:10 p.m. on Monday.
Firefighters encountered smoke coming from the four-story townhouse. Crews quickly extinguished the fire. Two people were home when the fire broke out, and escaped unharmed.
The occupants discovered the fire prior to the activation of smoke alarms. There were no injuries, officials said.
Damage is estimated at $15,000.
Investigators said the fire started when the lighting struck a natural gas line and entered a wall inside the home, causing the fire.
Around the same time Monday, lightning struck the visitors center and boathouse at Lake Fairfax Park in Reston. There was no fire and no injuries.