A motive was under investigation on Monday into the fatal shooting of a Pennsylvania state trooper who was gunned down during a traffic stop Sunday night by an alleged erratic driver who died at the scene by suicide, authorities said.

The trooper was identified by authorities as Cpl. Timothy O’Connor Jr., a 15-year-veteran of the Pennsylvania State Police.

“I am profoundly saddened to announce that tonight the Pennsylvania State Police family lost a son, lost a hero and lost a dedicated public servant,” Pennsylvania Gov. Josh Shapiro said at a Sunday night news conference.

The governor said the 40-year-old O’Connor, a married father of a young daughter, was killed “doing what he dedicated his life to and that is serving others, keeping our community safe, looking out for his fellow Pennsylvanians.”

O’Connor was shot during a traffic stop near West Caln Township in Chester County, Lt. Col. George Bivins of the Pennsylvania Police said at a news conference Sunday night.

Bivins said O’Connor was shot after he responded to a call around 8:16 p.m. near Honey Brook in Chester County. O’Connor located and stopped the vehicle around 8:24 p.m. near Route 10 in West Caln Township, Bivins said.

“He made a radio transmission indicating he was stopping the vehicle and that is the last we heard from Cpl. O’Connor,” Bivins said.

Bivins said a patrol officer was sent to check on O’Connor’s well-being “and found a very bad situation.”

A preliminary investigation found that “within seconds” of pulling the driver over, O’Connor was fatally shot, Bivins said.

The State Police identified the alleged gunman Monday afternoon as 32-year-old Jesse Nathan Elks of Honey Brook, Chester County.

“The driver opened fire from inside the vehicle, struck him just as he [O’Connor] approached the driver’s side of the vehicle,” Bivins said. “Cpl. O’Connor went down with a fatal wound immediately at the scene.”

Bivins said that after allegedly shooting O’Connor, the suspect got out of his car, walked a short distance and shot himself with a semiautomatic pistol. He was pronounced dead at the scene, Bivins said.

Detectives from the state police and the county are conducting a joint investigation into the shooting with the Chester County District Attorney’s Office.

“In the coming days, we are going to be looking into his background and his motives,” Chester County District Attorney Christopher de Barrena-Sarobe said Sunday.

Shapiro said he was at Paoli Hospital on Sunday night with O’Connor’s wife, Casey, and his parents.

“My heart breaks for Tim and Casey’s young daughter and their entire family,” Shapiro said in a statement.