A police officer was fatally shot on July 27 in Indianapolis while responding to a vehicle crash. (Reuters)

A routine call quickly turned tragic Thursday for Lt. Aaron Allan, a 38-year-old volunteer police lieutenant in Southport, an enclave of under 2,000 residents in Indianapolis.

Allan, who was named Officer of the Year in 2015, was fatally shot when responding to a report of a flipped car by one of the vehicle’s occupants.

Allan and an officer from the nearby Homecroft Police Department responded to the call about 3 p.m. Thursday, police said.

As Allan approached to offer assistance, one of its two occupants began shooting at him multiple times, fatally striking him, police said. It’s unclear what prompted the shooter to fire and further details were not immediately available.

Immediately, the Homecroft police officer, who has not been named, and an off-duty Johnson County Sheriff’s deputy who happened to be nearby, returned fire and hit the shooter. One witness told RTV6 there were at least 20 shots.

Both occupants suffered non-life-threatening injuries and were taken to the nearby Eskenazi Hospital in police custody, the Associated Press reported.

Bryan McGary, a resident of the neighborhood, told AP, “It’s just hard to believe that this would happen here. I mean I’ve lived here since 1976 and we really haven’t had much. We do have a lot of policemen in our area that live here so it’s just one of those things.”

Betty Strohm, another neighbor who called the shooting “devastating,” was also surprised.

“This is a great neighborhood,” Strohm told the Indy Star. “Everybody watches out for everybody here.”

Allan was widely praised by city officials at a news conference Thursday night, during which Indianapolis Metropolitan Police Chief Bryan Roach said of the ensuing investigation, “This will be handled just like one of our own officers.”

Police officer Lt. Aaron Allan at a ceremony in Southport, Ind. (Southport Police via Reuters)

Allan, who had wanted to be a police officer since he was 5 years old, spent six of his about 20 years in law enforcement with the Southport Police Department, a force comprised of about 30 volunteer officers. All of them work “with full police powers but without pay,” according to the Indy Star.

“It is with a heavy heart that I say this afternoon we lost a brother, Lt. Aaron Allan,” Southport Police Chief Thomas Vaughn said at the conference, recalling Allan’s nickname that so well described him: Teddy Bear.

He added, “Lieutenant Allan was a hard worker, and today was no different. He responded to a crash with urgency to preserve life. Tragically, his was lost.”

“It comes as just a complete shock,” Southport Mayor Russell McClure said at the news conference. “It’s just a tragedy you just can’t imagine happening to your city, to one of your officers.”

“Today, Lt. Aaron Allan was doing what officers do each day: responding to the scene of an accident to help someone in their time of need,” Indianapolis Mayor Joe Hogsett said in a statement on Twitter.

“His death is a shocking and tragic reminder of the difficult, often dangerous work of police officers across Marion County.”