Federal agents investigating an explosion in Nashville are searching a house for clues to why a motor home blew up and injured three people in the heart of America’s country music capital on Christmas Day.

The motor home, parked on a downtown street of Tennessee’s largest city, exploded at dawn on Friday moments after police responding to reports of gunfire noticed it and heard an automated message emanating from it warning of a bomb.

The thunderous, fiery blast destroyed several vehicles, damaged more than 40 businesses and left a trail of shards from shattered windows.

Following up on what they said were more than 500 leads, local police and agents from the FBI and US Bureau of Alcohol, Tobacco, Firearms and

Explosives were on Saturday searching a two-story house in Antioch, Tennessee, southeast of Nashville. Witnesses say they were paying particular attention to its basement.

Officials declined to name a person of interest in connection with the explosion but CBS News reported the investigation has honed in on 63-year-old Anthony Quinn Warner, who recently lived at the address, according to public records.

Google Street View images of the house from 2019 show what appears to be a white motor home in the driveway. Neighbours told TV station WKRN the recreational vehicle had been parked there for years and is now gone.

“Once we have processed the scene, we will look at the evidence and anything we have recovered from this residence and see how that fits into this investigation,” FBI spokesman Darrell Debusk said from the house.

“At this point we’re not prepared to identify any single individual,” FBI Special Agent in Charge Doug Korneski added.

Korneski told reporters investigators were “vigorously working on” identifying what appeared to be human remains found in the wreckage.

He declined to say if investigators believe the remains belong to the person behind what officials say was “an intentional act”.

Korneski said the FBI’s Quantico, Virginia-based Behavioral Analysis Unit was helping determine the motivation of the person responsible.

The vehicle was parked outside an AT&T Inc office, and the blast caused widespread telephone, internet and TV service outages in central Tennessee and parts of several neighbouring states, including Mississippi, Kentucky, Alabama and Georgia.

Adding to the cryptic nature of Friday’s incident was the eerie preamble described by police and witnesses – a crackle of gunfire followed by an apparently computer-generated female voice from the RV reciting a minute-by-minute countdown to an impending bombing.

Police scrambled to evacuate nearby homes and buildings and called for a bomb squad, which was en route to the scene when the RV blew up.
Police later posted a photo of the motor home, which they said had arrived in the area about five hours prior to the explosion.

Officials said 41 businesses were damaged and three people were hospitalised with relatively minor injuries.

-AAP

An earlier image attached to this story was an incorrect photo not of the suspect and has been removed.