One firefighter has been killed and nine others were injured after an explosion in a house where they were investigating a gas leak, US officials say.
Two civilians were also injured in the blast, which happened in Sterling, Virginia, at around 8pm local time on Friday (1am on Saturday UK time).
The fiery explosion occurred about 30 minutes after fire crews were called to the property due to reports of a gas smell.
It happened while firefighters were inside the building, James Williams, assistant chief of operations for Loudon County Fire and Rescue, said at a news conference.
“Soon after arrival, with firefighters inside, the house did explode,” Mr Williams said.
He added the nine firefighters and two civilians who were injured were taken to hospital with injuries ranging from “limited to severe”.
“We have all firefighters out of the building. The fire will continue to smoulder,” Mr Williams said.