The investigation authorities of the car bombing accident in Nashville, Tennessee, USA, have confirmed that they are investigating the explosion as a possible terrorist act, whether it is local or international.

The authorities said they believed that the bombing - which occurred on Friday morning - was deliberate, but did not know the motive behind it, and added that they had found body parts believed to be human near the scene of the explosion.

Explosion details

The blast, which shook the heart of the US country music capital, occurred only moments after officers moved to check reports of gunfire in the area and discovered the parked vehicle outside AT&T headquarters in central Nashville at around 6 a.m. CST. (12:00 GMT).

Nashville Police Chief John Drake told reporters that police heard a recorded message in the voice of a woman warning that "a bomb will explode within 15 minutes."

"This area must be evacuated now ... if you can hear this message, leave the area now," said the recorded message, which was later broadcast by local TV channels.

Police spokesman Don Aaron said that officers rushed to the homes to urge residents to move to safe places, and demanded that a squad of bomb squad experts be dispatched, which was on its way to the site when the vehicle exploded.

Fire officials said that 3 people were taken to local hospitals with minor injuries.

The authorities said that the police move swiftly to begin evacuating the area before the blast, most likely prevented further casualties.

The explosion caused massive damage to about 20 buildings, as well as disrupted the telecommunications network, and temporarily halted flights to and from the city's airport.

A federal investigation

The FBI took over the investigation into the explosion, which investigators described as unprecedented in the United States.

The office said on Twitter that its agents are helping to investigate and seeking information from digital media about the explosion.

Andrew McCabe, a former deputy bureau of investigation, told CNN that an explosion of this magnitude would be investigated as a possible terrorist act, on a local or international level.

He indicated that the police may be the likely target of the explosion, given that their personnel were verifying a report of a suspicious vehicle when it exploded.

For its part, Nashville police published a picture of the car that exploded in the middle of the city and called in a tweet for everyone who has any information about the car to report it.

She said that this vehicle arrived at Second Avenue at 1:22 pm after midnight, and asked everyone who saw it or had information about it to contact it on the phone number she attached to the picture.

The Al Jazeera correspondent said that experts and former security officials tend to classify the Nashville bombing as "domestic terrorism", due to its nature and the political messages it carries.

In a previous publication, he added that these experts believe that carrying out the bombing on a holiday and in an area frequented by a small number of people carries clues that the executing agency is keen not to cause casualties.

Nashville Mayor John Cooper has announced the imposition of a civil emergency in the area that witnessed the explosion.

The mayor said in a tweet on Twitter that he had signed an executive order to impose a curfew in the area from 4:30 pm on Friday evening to 4:30 pm tomorrow, Sunday (local time).

And the US Federal Aviation Administration decided to temporarily suspend flights to and from Nashville Airport, due to the telecommunications network being affected by the explosion.