NORTH CODORUS, Pa. (AP) — Three police officers were fatally shot and two wounded Wednesday in southern Pennsylvania, and the shooter was killed by police, authorities said.

The officers were at the scene, amid rolling farmland, to follow up on a domestic-related investigation that began the previous day.

“This is an absolutely tragic and devastating day,” Gov. Josh Shapiro said. “We grieve the loss of life of three precious souls who served this county, who served this Commonwealth, who served this country.”

“This kind of violence is not OK. We need to do better as a society,” Shapiro said at a news conference.

It was one of the deadliest days for Pennsylvania police this century. In 2009 three Pittsburgh officers responding to a domestic disturbance were ambushed and shot to death by a man in a bulletproof vest.

“The grief will be unbearable but we will bear it,” said Pennsylvania State Police Commissioner Christopher Paris, who pledged a full, fair investigation.

The shooting erupted in the area of North Codorus Township, about 115 miles (185 km) west of Philadelphia, not far from the Maryland line, authorities said.

York Hospital said it was treating two people in serious condition and had enhanced security protocols are in place.

Authorities did not identify the shooter, the officers or which police department they belonged to, or describe the circumstances of how they were shot, citing the ongoing investigation.

Shapiro said he and other officials met with the families of the slain officers and who, while grieving, took the time to say how proud their were of their loved ones.

Attorney General Pamela Bondi called the violence against police “a scourge on our society.” She said federal agents were on the scene to support local officers.

The emergency response unfolded on a rural road in south-central Pennsylvania. Officers were keeping people well back from the scene, with some 30 police vehicles blocking off roads bordered by a barn, a goat farm and soybean and corn fields.

A local school district issued a shelter-in-place order for a time, though it said schools and students were not involved in the shooting.

Another officer in the area was killed in February, when a man armed with a pistol and zip ties entered a hospital’s intensive care unit and took staff members hostage before a shootout that left both the suspect and an officer dead.

“We need to do better as a society,” Shapiro said. “We need to help the people who think that picking up a gun, picking up a weapon is the answer to resolving disputes. We need do better when it comes to mental health.

“We need to do better when it comes to looking out for those who are in need so we don’t have to deal with tragedies like this,” he said.