A Pennsylvania State Police trooper was shot and killed as he approached a car he had pulled over in a traffic stop Sunday night, authorities said.

Cpl. Tim O’Connor was killed when the driver fired from inside the vehicle, the state’s acting police commissioner, Lt. Col. George Bivens, said at an early Monday morning news conference at Paoli Hospital in Chester County.

The shooter — identified by police as Jesse Nathan Elks, 32, from nearby Honey Brook — then got out of the car, walked a short distance away and shot and killed himself with a pistol, Bivens said.

O’Connor was a 15-year veteran of the state police who was married and had a young daughter, authorities said.

“Anybody you talk to tells you what a great guy he was,” Bivens said.

Gov. Josh Shapiro said at the news conference that he told O’Connor’s wife, Casey, and parents that there were many questions about the shooting, “but the one thing that we absolutely know for certain is that their son, their husband, was a hero and he died protecting others.”

“That is a noble calling and that is something we are profoundly grateful for,” Shapiro said.

O’Connor, 40, joined the state police in 2010, state police said. He became the 105th member of the Pennsylvania State Police to be killed in the line of duty, the agency said.

O’Connor had been on patrol shortly after 8 p.m. Sunday night when a call came in for an erratic driver. O’Connor was dispatched and reported minutes later that he had pulled over the car at an intersection in West Caln Township, about 45 miles (72 kilometers) west of Philadelphia, Bivens said.

“That is the last we heard from Corporal O’Connor,” Bivens said.

He didn’t respond to ensuing radio calls and troopers dispatched to the scene to check on him “found a very bad situation,” Bivens said.

Police and Chester County authorities were investigating, Bivens said.

Chester County’s district attorney, Christopher de Barrena-Sarobe, said investigators will look into Elks’ background and motives.

Shapiro ordered U.S. and state flags to fly at half-staff to honor O’Connor.