A parked camper van exploded in the US city of Nashville, Tennessee early on Christmas morning in what police believe to be a deliberate act, APA reports citing BBC.
Officers arrived at the scene shortly after 06:00 (12:00 GMT) on Friday after reports of gunshots.
Police said the van was broadcasting messages warning it would explode when they arrived. It blew up a bit later.
Three people were injured, none of them critically, and have been taken to hospital, officials said.
Buildings and trees were damaged, and smoke rose above the city centre.
The FBI is leading the investigation. Agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives are also at the scene.
It was not clear whether anyone was inside the vehicle at the time of the explosion, police said.