Investigators found possible human remains near the site of where a motor vehicle exploded on Friday, CNN reported.A recording from a recreational vehicle emitted a chilling warning minutes before it all exploded, rocking downtown Nashville at dawn on Christmas Day and lightly injuring three people in what police described as an "intentional act."
"This area must be evacuated now. This area must be evacuated now. If you can hear this message, evacuate now. If you can hear this message, evacuate now" went the recording for several minutes, broadcast later on NewsChannel5, Nashville.
Police described the vehicle, parked in the heart of Tennessee's capital city at 6 a.m. CST (1200 GMT) on Friday, as an RV, a recreational vehicle of a type that could range from a motor home to a camper trailer.
Nashville Police Chief John Drake said the announcement warned the "bomb would explode in 15 minutes."
About the same time, police received an emergency call of "shots fired" in the downtown tourist area, said Nashville police spokesman Don Aaron. After arriving, they called in the bomb squad, which was on its way when the explosion occurred.
The blast ravaged the heart of the city, considered the capital of US country music. It destroyed several other vehicles and severely damaged several buildings, launching black smoke into the sky that could be seen for miles.
Fire officials said three people suffered minor injuries.
Moments before the blast, police officers went door-to-door in nearby buildings to hustle residents to safety and motioned a man walking his dog near the vehicle to change direction.
"Obviously, they heard the announcements coming from this vehicle," Aaron told reporters. "They took them seriously. And worked to seal the streets to protect folks and we think it worked." He called the blast "an intentional act."
Andrew McCabe, a former deputy FBI director, told CNN an explosion of this size would be investigated as a possible act of terrorism, whether domestic or international.
Police said it was unclear if anyone was inside the vehicle and the motive was unclear. McCabe said police may have been the target of the explosions given they were called to the scene before the blast.
Most of the buildings on the tree-lined street with shops and offices were closed given the hour and Christmas holiday.
The explosion, which could be heard for miles and felt nine blocks away, knocked one officer off his feet and caused what was hoped to be only a temporary hearing loss, the police spokesman said.
"There was trees lying everywhere, glass laying everywhere," Nashville resident Buck McCoy told CNN.
Nashville Mayor John Cooper urged people to stay away from the downtown area, as police and federal authorities investigated, aided by bomb dogs and surveillance camera footage.
President Donald Trump was briefed on the explosion, a White House spokesman said.
Car bombings in the United States are rare.
A 1995 truck bombing in Oklahoma City killed 168 people including 19 children, and wounded hundreds. Timothy McVeigh was executed by lethal injection in June 2001 for the attack.
In April 2010, a food vendor foiled an attempt to set off a car bomb in New York's Time Square.