Washington, Dec 26 (IANS): Authorities have found human remains near the site of what police believed was an intentional explosion that rocked downtown Nashville in the US state of Tennessee, according to multiple media reports.

It is not yet known whether the remains, now having been sent for medical examination, were related to the explosion on Friday that injured at least three people, reports Xinhua news agency.

Neither was it clear whether they belong to the suspected perpetrator or a victim.

Investigation was underway of the explosion which took place at 6.30 a.m. in the city's 2nd Avenue North area linked to a vehicle, the Metro Nashville Police Department (MNPD) tweeted.

"This appears to have been an intentional act," the force added.

A recorded message that indicated a bomb would explode in 15 minutes was heard coming from the recreational vehicle (RV) that exploded, MNPD Chief John Drake told a news conference.

"If you can hear this message, evacuate now," the warning broadcast from the RV said.

Officials have no information about whether anyone was inside the RV when it exploded, according to MNPD spokesperson Don Aaron.

Aaron also said "significant damage has been done to the infrastructure" on the street where the blast occurred.

Meanwhile, the Department of Justice (DOJ) said in the statement that Acting Attorney General Jeffrey Rosen has been briefed on the explosion "and directed that all DOJ resources be made available to assist in the investigation".