Susan Johnson was shot twice, in the arm and in the back, and was hiding behind a Christmas tree in her Biddeford apartment, left for dead, while her landlord fatally shot her son and his girlfriend, police revealed Monday.

The landlord, James Pak, 74 years old according to state police, had confronted the tenants angrily Saturday night at 17 Sokokis Road in Biddeford in a dispute about a parking place after a weekend snowstorm.

Biddeford police had responded to a call earlier that evening from one of the tenants, who told police Pak had threatened them. The officers left after the tenants said they did not believe they were in danger; but minutes later, Pak entered the apartment and threatened to shoot Johnson, according to an affidavit filed by state police Detective Corey Pike in support of Pak’s arrest.

Pak — who police say had been drinking — shot Johnson twice, then fired two shots each into Johnson’s son, Derrick Thompson, 19, and his girlfriend, Alivia Welch, 18, police said. Both died of gunshot wounds to the chest, accoding to the Office of the State Medical Examiner.

Johnson told police she “heard Welch scream, ‘Don’t shoot; stop,’ and then heard two more gunshots,” according to the affidavit.

Pak spoke “freely” to police after his arrest, telling them he had killed three people. He was apparently unaware that Johnson was alive. He said he “spared” the life of Johnson’s other son, 7-year-old Brayden, who was also in the apartment, according to the affidavit.

Johnson told police that Pak used a silver-colored handgun with a white handle. Police found a Smith and Wesson revolver in a downstairs bathroom with the hammer still cocked back and red-brown stains on it, the affidavit says. They also found a rifle and shotgun in a basement crawl space.

More than two hours after Pak’s arrest, his blood-alcohol content level was 0.15, nearly twice the legal limit, the affidavit says.

Pak, who owns the house on Sokolis Road and also lives there, appeared Monday in York County Superior Court to face two counts of murder. He appeared before Justice Paul Fritzsche with his attorney, Joel Vincent.

Dressed in a blue jacket, the 5-foot, 4-inch, 160-pound Pak was silent in court. He is due in court again March 22, unless he is indicted before then.

Pak was not required to enter a plea. If convicted, he faces 25 years to life in prison. He is being held without bail at York County Jail pending a hearing to determine whether he can be held until trial.

Although state police and jail officials list Pak’s age as 74, his driver’s license and prior police contacts list his age at 67. Authorities could not explain the discrepancy.

Other details about the events of Saturday night also came to light Monday.

Derrick Thompson apparently initially called Biddeford police at 6:07 p.m. Saturday to report that Pak was banging on his door, yelling and threatening him. Johnson recorded the confrontation between Thompson and Pak on her cellphone before police arrived.

Officers Edward Dexter and Jacob Wolterbeek responded to the initial call and determined it was a civil dispute, apparently about the number of cars parked in the driveway and late rent.

“Thompson told Officer Dexter that Pak got in his face and told Thompson to hit him,” the affidavit said. “Thompson told Officer Dexter that Pak claimed he was going to shoot them and made a hand motion in front of them.”

“Thompson told Officer Dexter he was not fearful and did not believe that Pak would do anything that he claimed,” the affidavit said.

Deputy Chief JoAnne Fiske, in summarizing the police report, said Monday that the two sides were told to keep their distance from one another.

“Derrick and Susan were advised, if the harassment continued, to call (police). Both Derrick and Susan said they did not feel threatened,” she said.

Dexter left the apartment at 6:50 p.m., telling a dispatcher he would file a report on the incident.

Three minutes later, Johnson called police to report that she had been shot in the back and her landlord was armed with a pistol.

Police returned to the house within a couple of minutes. Pak’s wife called police to say her husband was not threatening her but said he was going to kill himself, the affidavit said.

She got out of the house and was led by police to safety, Beaupre said.

With Pak in the main house, Dexter went into the apartment and found Johnson’s son Brayden hiding, although it’s not clear where he was. Dexter got him to a neighbor’s house for safety, Beaupre said. Dexter, who also is trained as a paramedic, then found Johnson hiding behind the tree. He performed emergency medical treatment, then carried Johnson outside and down the street to a waiting ambulance.

Officer Scott Evans found Thompson and Welch and determined they were dead.

Meanwhile, Sgt. Normand Allaire, who was off duty but in the area, was summoned to negotiate with Pak. Pak admitted shooting the three adults in the apartment, the affidavit said.

After three hours of negotiations, Pak agreed to come out. He initially said he would bring the gun out with him but was warned not to, Beaupre said.

As he walked down his driveway toward the police, Pak refused commands to take his hands out of his pockets, Beaupre said. He turned as if to go back inside the house, and Officer Scott Evans, who had walked up behind him, used one of the department’s newly issued Tasers to disable him. He was then handcuffed.

Johnson was taken to Maine Medical Center, where she was listed in stable condition Sunday night. The hospital on Monday said she was no longer there. Authorities say she probably was discharged or transferred.

Biddeford Police Chief Roger Beaupre said police respond to disputes every day involving tenants, landlords and neighbors, and there were no red flags that night to suggest the confrontation would escalate. Pak has no previous criminal or mental health history that would have given police cause for concern, he said.

“This time of year, people push snow into their parking spaces, like in the fall we get complaints of leaves blowing on other people’s property,” Beaupre said. He noted that the shooting took place in a middle-class neighborhood of single-family homes on the outskirts of town, not in the dense city core.

“It can happen anywhere,” he said.

Police intend to analyze the incident to determine whether they might have missed something and what might be done better, he said.

Beaupre said he saw nothing in the department’s call log to indicate police had responded to Pak’s house before Saturday. Beaupre said Pak does not have a concealed weapons permit, but noted that because he was at home, he would not have needed one.

Friends of Thompson and Welch plan to hold a candlelight vigil Monday night at Clifford Park in Biddeford.

Thompson graduated in 2011 from the alternative pathways program at Biddeford High School. He worked as an auto detailer for Real Clean, a company that provides cleaning services for Patriot Subaru in Saco.

Welch graduated from Thornton Academy in June and was a pre-nursing student at Southern Maine Community College. She worked at Aroma Joe’s in Biddeford.

Welch and Thompson had dated since at least last spring. They referred to themselves as married on Facebook, even through they were not. Welch had been staying with Thompson for the past month.

Thompson’s family moved into the Sokokis Road house in October. Welch had been staying there for about a month, according to police.

Portland Press Herald Staff Writer Gillian Graham contributed to this report