NASHVILLE – Authorities believe an explosion that occurred in downtown early Christmas morning and was felt for miles was an “intentional act” sparked by a vehicle.

Police responded to reports of a suspicious vehicle parked outside the AT&T building just before 6 a.m. Upon arrival, police said an officer “had reason” to alert the department’s hazardous devices unit, which was en route, when a “significant explosion” happened.

Three people were hospitalized with injuries, police said. At least 20 buildings were estimated to be damaged due to the explosion.

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Police and firefighters responded to an area near Second Avenue and Commerce Street about 6:45 a.m. Friday. Officials are on the scene trying to put out the fire and see if anyone is inside the building.

The fire department confirmed a bomb squad was on the scene with an active investigation by Metro police and federal agencies. The department asked residents and others to avoid the area.

Mayor John Cooper said he toured the damage, describing broken glass and water mains with insulation “blown up” into the trees.

“It looks like a bomb went off,” he said. He said it was too soon for any conclusions but said updates will be given Saturday morning.

The downtown area will be “sealed off” for further investigation and to make sure everything is “completely safe,” according to Cooper.

“One more event in Nashville’s 2020,” he said.

Images and videos taken in the area showed flames and smoke — which could also be seen from miles away. Alarms inside several buildings were heard going off with water pouring into some buildings with structural damage and broken windows. Debris and shattered glass were seen flying over a wide area.

Trees lining Second Avenue were blackened from the incident.

The owner of the nearby Nashville Downtown Hostel told The Tennessean, part of the USA TODAY Network, guests were evacuated to Nissan Stadium for shelter. He said he got a call early Friday from his staff who reported hearing a “loud boom” and the fire alarm going off.

He said the hostel is damaged but did not go into details.