WEST CALN TOWNSHIP, PA — A Pennsylvania state trooper was fatally shot during a traffic stop Sunday night in Chester County, authorities said.

A driver in a stopped vehicle shot and killed State Police Cpl. Timothy O’Connor before killing himself, authorities said. Investigators described the incident as a murder-suicide.

Troopers had been called around 8 p.m. Sunday about an erratic driver in Honey Brook. They pulled over the 32-year-old driver in West Caln Township.

Shortly after, the driver shot and killed O’Connor as he approached the vehicle, State Police Lt. Col. George Bivens told reporters.

“Within seconds, as he approached the car, the driver opened fire from inside the vehicle and struck him just as he approached the driver’s side of the vehicle,” Bivens said, according to ABC7.

The driver then got out of the vehicle, walked a short distance and shot himself, Bivens said.

State Police and the Chester County District Attorney’s Office are investigating the circumstances of the incident.

Gov. Josh Shapiro said he was at Paoli Hospital with O’Connor’s wife and parents Sunday night.

“Tonight, Pennsylvania tragically lost one of our finest when State Police Corporal Tim O’Connor was killed in the line of duty,” Shapiro said.

Shapiro directed all flags across Pennsylvania to be lowered Monday in O’Connor’s honor.

This is a developing story. Check back for updates.