An explosion on Friday morning at 6:30 am rocked downtown Nashville in the United States, causing damage to the nearby buildings, reported local media. The explosion took place outside The Melting Point restaurant.

The motorhome exploded, shattering windows and injuring three people in what police described as an “intentional act,” as investigators searched for clues among scattered debris.

The blast left glass, tree branches and bricks were strewn across the street in an area filled with businesses, restaurants and bars.

Authorities have found what they believe to be human remains near the site of the explosion, according to two law enforcement officials familiar with the ongoing investigation. The remains have been sent to the medical examiner’s office for analysis,CNN reported.

Authorities said they had received a phone call warning that a parked recreational vehicle (RV) was set to explode in 15 minutes. The RV itself began broadcasting an apparently recorded repeating message for anyone nearby to stand away, The Guardian reported.

As Nashville police officers cleared the area of residents, the vehicle exploded.

“We had one officer that was knocked to the ground and we are currently sweeping the area to make sure everyone is safe,” said a Nashville police spokesman, Don Aaron, as per The Guardian inputs.

Aaron said police are not aware of other threats to the public, but bomb dogs swept the area as a precaution. Authorities could not say if anyone was in the vehicle when it exploded.

Pictures shared on social media from the immediate aftermath showed thick plumes of black smoke rising from the burning RV and storefronts that had been badly damaged.

US President Donald Trump was briefed on the incident, which is being investigated by the FBI and the US Bureau of Alcohol, Tobacco, Firearms and Explosives in addition to the metropolitan police.

Although the agents couldn’t offer any possible motive immediately and made no link to any terrorism plot.

“This appears to have been an intentional act. Law enforcement is closing downtown streets as the investigation continues,” the Metro Nashville Police Department tweeted.

Firefighters said at least three people were taken to the hospital with minor injuries, according to local media.

The blast was large enough to be felt several blocks away but the early hour meant streets were largely empty.

The damage was “limited but it is dramatic,” Nashville Mayor John Cooper said, adding that the city was “lucky” the blast had occurred on Christmas when few people were downtown, AFP reported.

“It’s unfortunate but any other morning I think it would have been a much worse story.”

Police said several people had been moved to a local station for questioning, although no arrests or details of suspects were announced.

US Senator Marsha Blackburn of Tennessee led messages of concern from multiple public figures, saying she was “praying for all those involved” and thanking the “brave first responders for keeping us safe.”