NASHVILLE, Tenn., Dec 26 (Reuters) — Federal agents were investigating over 500 tips and scouring the charred site of an explosion in Nashville, a day after a motor home blaring a recorded warning blew up and injured three people in the heart of America's country music capital on Christmas Day.

Hundreds of agents and local police officers are involved in the probe of Friday's fiery, thunderous blast, which destroyed several vehicles, damaged more than 40 businesses and left a trail of glass shards.

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 the recreational vehicle and heard an automated message emanating from it warning of a bomb.

FBI Special Agent in Charge Doug Korneski told reporters on Saturday that investigators were "vigorously working on" identifying what appeared to be human remains found amid the wreckage, but he did not say whether the remains were thought to belong to the person behind what officials say was "an intentional act."

Korneski said the FBI’s Quantico, Virginia-based Behavioral Analysis Unit had been brought in to try to determine the motivations of the person responsible. Officials are still working to identify a suspect and the mechanism of attack.

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CBS News reported on Saturday that 63-year-old Anthony Quinn Warner, a Nashville area resident, was a person of interest tied to the explosion, citing unnamed law enforcement sources. Warner had a recreational vehicle similar to the one officials identified at the site of the blast, CBS reported.

Reuters could not immediately confirm the report, and officials declined to identify a person of interest on Saturday afternoon.

"At this point we're not prepared to identify any single individual," Korneski said, noting that officials were following up on 500 leads and looking at "a number of individuals" in possible connection to the explosion.

Dozens of agents from the FBI and the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives were surveying the ashy disaster area on Saturday. Inside the area, which was blocked off to traffic, parked cars and trees were blackened and an exploded water pipe that had been spraying overnight had covered trees in a layer of ice.

A total of 41 businesses were damaged, Mayor John Cooper said.

"All the windows came in from the living room into the bedroom. The front door became unhinged," Buck McCoy, who lives on the block where the blast occurred, told local TV station WKRN. "I had blood coming from my face and on my side and on my legs and a little bit on my feet."

Tennessee Governor Bill Lee said he toured the disaster zone on Saturday, saying in a Twitter message it was a "miracle" that no one was killed. In a letter to President Donald Trump, Lee requested a federal emergency declaration for his state to aid in relief efforts.

A recording, then a blast

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 still en route to the scene when the RV blew up just outside an AT&T Inc office building where it had been parked.

Police later posted a photo of the motor home, which they said had arrived in the area about five hours prior to the explosion.

Fire officials said three people were hospitalized with relatively minor injuries and were in stable condition. Authorities said police likely prevented more casualties by acting quickly to clear the area of bystanders.

The explosion's damage to AT&T's facilities caused widespread telephone, internet and fiber-optic TV service outages in central Tennessee and parts of several neighboring states, including Mississippi, Kentucky, Alabama and Georgia.

AT&T's efforts to restore services overnight were waylaid when a fire reignited at the company's downtown office at the site of the blast. The company said in a statement on Saturday that it was deploying portable cell sites to downtown Nashville and across the region.

(Reporting by Harrison McClary in Nashville and Gabriella Borter in Fairfield, Conn.; Additional reporting by Rich McKay in Atlanta and Raphael Satter, Katanga Johnson and Lucia Mutikani in Washington Writing by Steve Gorman and Gabriella Borter Editing by Daniel Wallis, Matthew Lewis and Leslie Adler)