Hofstra student John Kourtessis described a chaotic scene of fear and horror when a crazed parolee in a ski mask took his friends and him hostage in a gunpoint siege that ended with the death of a pretty co-ed.

“Somebody in this house f–ked up and owes this Russian guy $10,000,” yelled Dalton Smith, who was on the run after violating parole last month.

“I was trying to calm everyone down, like, ‘Don’t worry, just give the guy what he wants and we’re going to get out of here,’ ” Kourtessis recounted to The Post.

But there was no averting tragedy. Minutes after the incident began, Smith and Andrea Rebello, 21, were dead.

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The horror unfolded after a night of drinking at a bar, McHebe’s, a hangout for Hofstra University students where Rebello, her twin sister, Jessica, their friend Shannon Thomas, Andrea’s boyfriend Brad Wilson and Jessica’s boyfriend, Kourtessis, partied to mark the end of the school semester.

“We were supposed to be celebrating because school was out, but Andrea wasn’t having the best night,” said Wilson, 22, a marketing major.

“She just had something bothering her. So I was there, just doing what I could to help make her feel better. I tried making her laugh.”

Wilson broke off from the group at about 2 a.m. after they left the bar. The rest stopped a 7-Eleven for late-night snack and headed to the tiny, two-story house the girls shared in Uniondale, LI.

“We never got a chance to say goodbye,” Wilson said.

At the house, Jessica asked Kourtessis to move his car.

He ran upstairs to get his keys. When he came back down, Kourtessis said, Smith was there, waiting.

Smith kept talking about “the Russian guy,” Kourtessis recalled.

The parolee claimed the house’s residents owed the Russian money, that the Russian was waiting outside and that the debt was due “by the end of the night.”

His claims made no sense to anyone, but Smith’s semiautomatic gun was hard to ignore.

Kourtessis said he found himself in a kind of survival mode.

“I didn’t hear screaming,” he recalled. “I just don’t remember hearing screaming. I had tunnel vision.”

Kourtessis tried to appease Smith. “He was saying . . . that he just needed us to cooperate. I said, ‘Listen, we have all this money here.’ ”

They offered up the computers, jewelry and other items in the house, Kourtessis said, explaining to the thug, “This is worth $3,000, this is worth $1,500, we’re almost there.”

Andrea, Jessica and Thomas were crying. Smith kept demanding more money. But none of the young people had enough to satisfy him.

“So he says. ‘Where’s the jewelry?’ ” Kourtessis recalled.

They moved upstairs, menaced all the while by Smith’s gun.

The crook asked who had money in the bank. Shannon said she could get $700 from an ATM. Smith told her to go get it.

Shannon ran from the house, drove off and called 911.

Moments later, in the house, Andrea, Jessica and John heard a noise outside. Thinking Shannon had returned, Jessica went to the door. Instead, Jessica found police officers — so she ran to safety.

Realizing the police had arrived, Smith freaked out.

“I can’t go back to jail! One of you, get over here,” Smith said, according to Kourtessis’ account.

“So I get up and come over and he puts me down with the gun to the back of my head,” Kourtessis said. “He said, ‘Show them your hands and tell the cops to get out of there.’ Then he does the same to Andrea.”

Smith, whose rap sheet lists robbery and assault charges dating to 1999, asked for a way out of the house.

Kourtessis offered an escape route. “Crawl and show me,” Smith commanded.

Slowly, Kourtessis made his way down the stairs, making a left at the bottom.

“I see an officer there, with his gun out, standing by the steps. So I’m thinking, ‘Good, there’s a cop there,’ ” he said.

“I run behind the L-shaped couch and I see the cop pointing his gun toward the TV.”

Smith also made his way down the stairs — holding Andrea in a headlock and using her as a human shield, police said. The officer began talking to Smith, saying, “Put the gun down and let the girl go.”

“I’m going to kill her,” Smith replied. Kourtessis ran into a bedroom. Then he heard the shots.

“I hear ‘pop, pop’ — two shots,” he said. “I run out and I run toward where they are.”

By then the cop had maneuvered the criminal into the basement area of the home, said Kourtessis. He then watched as the officer shot twice more. He saw other officers outside, and dropped to the floor.

“Andrea! Andrea!” he screamed.

But Andrea didn’t answer.

Both Smith and Andrea were felled by bullets fired by a Nassau officer, cops said.

Records show Smith, 30, was released from prison in February after serving more than 8 years in the slammer for attempted armed robbery, and cops said he quickly violated parole, prompting a warrant for his arrest.

The career criminal also served time previously for crimes including auto theft.

After the shooting, cops swarmed into the house, handcuffed Kourtessis and began a search.

The stunning episode just days before Hofstra’s commencement sent shock waves through the school.

Andrea’s family huddled at their Westchester home, refusing to comment to media as visitors brought food and flowers. Four detectives visited the family late yesterday.

For Wilson, it was a tragic end to his 2 1/2-year romance with the beautiful young woman from Tarrytown.

“Andrea had the biggest, brightest smile and she was so smart. She practically lived in the library, always into her books and studying hard.

Andrea had planned to soon move from the home where she died.

“I really wish she moved out sooner,” said Wilson.

“She had so much love and she showed it to everyone. She was pure and innocent and deserved everything good in this world. I will never forget about her, and she will always have a big piece of my heart.”

Additional reporting by Erin Calabrese, Candice Giove, Candace Amos and Kathianne Boniello