Pennsylvania cop-killing gunman identified as 24-year-old Matthew James Ruth

Ruth, who was killed in a shootout with police, was seen on Tuesday night lurking outside the girl's house dressed in camouflage, equipped with binoculars, and armed with an AR-15 rifle, according to an affidavit, the New York Post reported.

Prosecutors had charged Ruth shortly before the ambush with stalking, prowling at nighttime, and criminal trespass, according to court records. Police returned to the scene on Wednesday to serve the warrant as part of their investigation, but were met with heavy fire.

According to York County District Attorney Dave Sunday, Ruth had concealed himself in the girl's home, lying in wait to ambush the officers when they arrived. Neighbors reported hearing at least 30 rounds of gunshots. The girl Ruth briefly dated said she had never invited him over to her house, police said.

Ruth fatally wounded three detectives, identified as Sgt. Cody Becker, Mark Baker, and Isaiah Emenheiser. Two additional officers—a sheriff's deputy and another detective—were injured but survived, with one in critical condition.

"Yesterday was a dark and heartbreaking day for the Northern York County Regional Police Department and for all of York County," the department said in a statement.

Gov. Josh Shapiro also weighed in on the tragedy, saying, "This kind of violence isn't okay. We need to do better as a society."

"We need to help the people who think picking up a gun, picking up a weapon is the answer to resolving disputes," he continued. "So we don't need to deal with tragedies like this."