The gunman who killed three Pennsylvania police officers ambushed police the moment they opened the front door to the house of his stalking victim, which was empty except for the dead family dog he fatally shot, officials revealed Thursday.

Det. Sgt. Cody Becker, Det. Mark Baker and Det. Isaiah Emenheiser, of the Northern York County Regional police force, were identified as the victims of Matthew Ruth, who opened fire on them when they began walking into the unlocked North Codorus home during a domestic violence probe Wednesday, said York County District Attorney Timothy Barker at a press conference.

Another Northern York detective and a York County sheriff’s deputy were also critically wounded during the barrage of gunfire that lasted for two minutes until Ruth was fatally hit, said Barker.

Northern York Police Chief David Lash said the community was “forever indebted” to the three slain detectives.

“Each of these men represented the very best of policing,” he said, his voice cracking and his sadness splashed across his face. 

“They served with professionalism, dedication and courage. They were leaders within our agency, committed to protecting this community and standing beside their fellow officers.”

The investigation into Ruth leading up to the fatal confrontation began the previous night when police visited the same home, where Ruth’s ex-girlfriend lived, on a report of a man lurking outside her house with an AR-15.

Authorities couldn’t find Ruth Tuesday night, and he also wasn’t at his home when police stopped by the following afternoon after issuing a warrant for his arrest on stalking.

Law enforcement, including the three slain detectives, then went back to the victim’s home.

They realized the door was unlocked even though it was locked when the ex and her mother had fled the home earlier for their safety.

“They decided that they were going to go in. The door was opened and upon immediately opening the door, the actor repeatedly fired at the officers multiple rounds from an AR-15 style rifle with a suppressor,” DA Barker said.

Ruth kept squeezing the trigger as police attempted to retreat with another Northern York County detective who was also struck by gunfire, Barker said.

The gunman then turned his attention to the York deputy sheriff and another Northern York detective, leading to an exchange of gunfire outside, he said. The deputy was shot near his vehicle, but was still able to get off rounds as he ducked for cover.

A final exchange of gunfire took place with the Northern York detective when Ruth reached near the roadway.

“After that exchange, the actor went down,” said Barker, who refused to use Ruth’s name throughout the news conference. “The actor became deceased.”

The Northern York detective then rushed to give aid to his fallen colleagues, but found Baker, Becker and Emenheiser unresponsive after a “barrage of murderous activity,” said Barker.

In another cruel twist, the family’s black labrador was found shot dead inside the basement of the home.

The prosecutor made clear that the killed and wounded police officers were heroes who saved the life of Ruth’s stalking victim.

“We have two lives of the residents there that are saved today. Had they arrived home and not Northern Regional Police Department officers arrived, they would have been killed immediately by the actor,” he said of the ex-girlfriend and mother.

“That is not speculation, that is the absolute only reasonable inference from all actions.”

Baker was a father of four, according to WPN while Becker was a former Spring Grove football player who as a cop caught a baby and two children during a 2010 fire, the York Daily Record reported.  

Emenheiser was shot at by a suspect in 2018, but wasn’t’ hit, according to the York Daily Record.  He was named Officer of the Year in 2011, and a year earlier had received the DUI Top Gun honor — an award he went on to earn three more times for his record DUI arrests, WHP reported.