A new video of the Christmas morning blast in the US city of Nashville has emerged on the Internet.
The footage shows what looks like a police officer walking down the street against the background of a parked RV and a police car.
Later the policeman is seen exiting the frame, which is followed by a powerful explosion, with thick black smoke and flying debris.
Before the vehicle exploded, a pre-recorded warning urged people in the area to evacuate.
The FBI is investigating the explosion, which could possibly have been a suicide bombing, CNN cited unnamed sources as saying.