ATLANTA/WASHINGTON/TENNESSEE (REUTERS) - 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 6am CST (1200 GMT) on Friday (Dec 25), 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. The victims had been taken to local hospitals and their condition was stable.
Authorities said it was uncertain whether anyone was inside the recreational vehicle when it exploded, but police reported hours later that investigators had found possible human remains nearby.
Nashville Mayor John Cooper ordered a curfew imposed around the blast site through the holiday weekend as FBI investigators comb the scene, though police said they were aware of no further threats to Tennessee's most populous city.
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 that the motive for the blast was unclear. McCabe said police may have been the target of the explosions given they were called to the scene before the blast. There had also been no claims of responsibility.
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.
Another resident, Betsy Williams, told CNN that she was awakened by the sound of gunfire and looked out her window to see an RV parked across the street as it began playing a message delivered by a "computerized" female voice. She said the voice warned the vehicle contained a bomb and started a minute-by-minute countdown to the actual explosion.
"Everything shook, it was quite a blast," she told CNN.
The fiery blast destroyed a number of other vehicles parked nearby, shattered windows and heavily damaged several adjacent buildings, sending a pall of black smoke into the sky that could be seen for miles. The mayor said a total of 41 businesses were damaged.
At an early evening briefing, Drake, the police chief, told reporters there were "no fatalities we know of," but said investigators were examining "tissue that we believe could be human remains" found in the vicinity of the blast.
Police said they had not ascertained whether anyone was in the motor home when it exploded.
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 Times Square.