NASHVILLE, Tenn. (WKRN) – A witness spoke to News 2 on what he heard and saw regarding an explosion that happened in downtown Nashville Christmas morning that rattled the city.

Brian Norwood lives in an apartment building in the area of 2nd and 1st avenues and said he heard three rounds of gunfire before the explosion.

“I thought it was somebody slamming door or something,” he said regarding the first round.

However, 10 minutes after the first round of shots, a second round was fired.

“Then around 10 minutes later, there was a whole another round of gunfire – this time more gunfire and louder. And we got scared and got out of bed and barricaded the door to our apartment,” Norwood said.

Then around 15 minutes after the second round of shots, a third round of shots were fired. This time, however, more shots were fired than the first two rounds.

“The first time it was three shots; the second time it was five shots. The third round it was probably about 10 or 15 shots, and we were petrified. We were sitting in our apartment with our door barricaded with the lights out, not talking because we were scared to make noise.”

Police then went inside Norwood’s building around 20 to 30 minutes later and started knocking on doors, alerting residents to get out of the building. Police told residents to leave the building out the back way and go toward 1st Avenue, not 2nd Avenue.

Norwood’s car was parked across town in The Gulch. After reaching his car and getting into it, that’s when Norwood said the explosion happened.

“We had been sitting in the car for about 10 minutes and then our whole car shook,” he said. “It felt like a bomb went off, and we looked over toward 2nd Avenue from The Gulch, and we saw flames and like sparks.”

At around 6:30 a.m. Friday morning, an RV exploded near the intersection of 2nd Avenue and Commerce Street.

Police say officers were initially in the area investigating a shots fired call when the explosion happened. Three people have been taken to the hospital with non-critical injuries. The explosion is believed to have been an intentional act.

Access to downtown is restricted as authorities continue to investigate.

The Federal Bureau of Investigation is the lead in the investigation. Anyone with information should call 1-800-CALL-FBI.