WATCH: Pennsylvania officials give update on shooting that left 3 police officers dead

Three police officers were fatally shot and two wounded Wednesday in southern Pennsylvania, and the shooter was killed by police, authorities said.

Watch the news conference held by York County District Attorney Tim Barker in the video player above.

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

They opened the door and were immediately fired upon by the suspect, 24-year-old Matthew James Ruth, who was carrying an AR-style rifle with a suppressor, York County District Attorney Tim Barker said.

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He said the suspect fired multiple rounds at the four officers at the door, killing three of them. A gunfight then ensued between Ruth and two officers outside. Ruth wounded a sheriff’s deputy before police shot the gunman to death, Barker said.

Detective Sgt. Cody Becker, Detective Mark Baker and Detective Isaiah Emenheiser were the officers who were killed, he said. They all worked for the Northern York County Regional Police Department.

“Each of these men represented the best of policing. They served with professionalism, dedication and courage. They were leaders within our agency, committed to protecting this community and standing beside their follow officers,” Chief Dave Lash said of the three slain Northern York Regional police officers.

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.

Condolences began pouring in from police departments across the region on social media and people began leaving flowers at the headquarters of the Northern York Regional Police Department.

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.