Six Nashville, Tenn., police officers were hailed as quick-thinking and fast-acting heroes Friday, credited saving lives and limiting injuries in the downtown area after a shocking Christmas morning explosion that remained a mystery Saturday morning.

"These officers didn't care about themselves," Metro Nashville police Chief John Drake told FOX 17 in Nashville. "They didn't think about that. They cared about the citizens of Nashville."

The police officers went door-to-door to evacuate residents and called in a bomb squad after spotting a suspicious recreational vehicle that was parked on a downtown street. Soon after, the RV exploded in a tremendous blast that damaged several buildings.

Police were already in the area, responding to a call of shots fired in the early hours of Friday morning when they encountered the RV, which Drake said, "had a recording saying a potential bomb would detonate within 15 minutes."

VEHICLE PLAYED RECORDING SAYING BOMB WOULD DETONATE, UNKNOWN IF SOMEONE INSIDE RV: POLICE

One officer, according to police, experienced hearing loss from the explosion and it was unclear whether the injury would be temporary or permanent. No other officers were hurt.

The six officers were identified as: Officer Brenna Hosey (4 years of service); Officer James Luellen (3 years); Officer Michael Sipos (16 months); Officer Amanda Topping (21 months); Officer James Wells (21 months) and Sgt. Timothy Miller (11 years).

Clockwise, from upper left: Nashville police Officer James Wells, Sgt. Timothy Miller, and officers Brenna Hosey, Michael Sipos, James Luellen and Amanda Topping.

Clockwise, from upper left: Nashville police Officer James Wells, Sgt. Timothy Miller, and officers Brenna Hosey, Michael Sipos, James Luellen and Amanda Topping.

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A police spokesman told reporters that moments before the explosion, an officer redirected a man and his dog who were walking in the area of the RV.

"Obviously they heard the announcements coming from this vehicle, they took them seriously and were working to seal the streets to protect folks, and we think it worked," a police spokesman told reporters. "We think lives were saved by those officers doing just that."

EXPLOSION THAT ROCKED DOWNTOWN NASHVILLE ON CHRISTMAS MORNING APPEARS TO BE 'INTENTIONAL ACT,' POLICE SAY

Three total people suffered minor injuries.

Police say they believe the explosion was intentional.

"Thank God for our police. I would say Back the Blue," country star and Nashville bar owner John Rich said on Fox News' "America's Newsroom." "I would say this is why you don't defund the police. You have to have them in situations like this when they're the only ones keeping watch over the safety of the citizens. So God Bless Metro Nashville Police Department, we've all got their back."

Sen. Marsha Blackburn, R-Tenn., told Fox News she was "so grateful" for law enforcement, calling them the "thin blue line that continues to stand between chaos and calm."

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"It could have been much worse," said bar owner Joey DeGraw. "Some police officer obviously had his eyes peeled and picked out something suspicious, thank God."

The FBI has taken over the investigation into the explosion.