BREAKING: Human remains discovered near Nashville blast site

It is not clear if the remains belong to a victim or a person responsible for the blast which authorities have called “an intentional act.” Three people were taken to area hospitals for treatment after the blast, although none were listed in critical condition. Authorities have not said if anyone was inside the RV when it exploded. Authorities added that some people were taken to the department’s central precinct for questioning but declined to give more details.

In a briefing earlier Friday, Nashville’s police chief said officers responded to what turned out to be a false report of a shots fired before discovering an RV that was amplifying audio warnings over loudspeakers that a bomb would detonate in 15 minutes. Nashville police evacuated nearby buildings and requested the bomb squad. Shortly thereafter the RV exploded.

A surveillance video circulated social media Friday that appeared to be taken across the street from the blast and recorded the warning issuing from the RV, “... if you can hear this message, evacuate now,” seconds before the explosion.

The blast sent black smoke and flames billowing from the heart of downtown Nashville. CBS affiliate WTVF reports the blast was felt across much of Davidson County around 6:30 a.m. The American Red Cross of Tennessee announced that it was working with officials to open a shelter for victims of the blast.

The blast occurred near a building owned by AT&T which released a statement Friday on about outages caused by the blast. "Service for some customers in Nashville and the surrounding areas may be affected by damage to our facilities from the explosion this morning. We are in contact with law enforcement and working as quickly and safely as possible to restore service."

The outages affected phone and internet service across parts of Tennessee and Kentucy, including some EMS and air traffic control communication services.

Flights have also been suspended out of the Nashville International Airport due to the day's events, and flights coming in have been put under a management program. Nashville International Airport told WKRN it had activated "enhanced security protocols." The FAA tweeted the following, which has been confirmed on their website.

Authorities tweeted a photo of the RV, which police said arrived on 2nd Avenue at 1:22 a.m. Central time.

Agency spokesman Joel Siskovic said that the FBI will be taking the lead in the investigation. Federal investigators from the Bureau of Alcohol, Tobacco, Firearms and Explosives were also on the scene.

Tennessee Gov. Bill Lee said on Twitter that the state would provide the resources necessary “to determine what happened and who was responsible.”

FBI Assistant Special Agent in Charge Matt Foster said at a briefing, "We're putting everything we have into finding who was responsible for what's happened here today. As part of doing that, there are investigative leads to be pursued. There's also technical work that needs to happen." He urged anyone with information to go to www.fbi.gov/nashville or call 1-800-CALL-FBI to provide tips.