A drunken off-duty cop plowed his SUV into four people on a Brooklyn sidewalk early Saturday, killing one person and leaving three others in critical condition.

The dead victim was a 21-year-old man whose family isn’t yet aware of his fate because his parents are hiking in California, sources said.

The wasted officer, rookie Nicholas Batka, was not too drunk to realize what he had done. “Did I kill anybody?’’ he asked the first cops who pulled up, one source said.

Batka, 28 — who had been due at work at 7 a.m., four hours after the horror — tried to flee the gruesome scene in Williamsburg but couldn’t move his car, witness Kelly Convery said.

So “he switched sides, from the driver’s seat to the passenger side,’’ she said. “Everyone saw him do it.”

Brandon Smith, who lives on the block, said, “People were trying to stop him’’ from fleeing.

One held the door of the Dodge Durango shut so he couldn’t escape, another witness said.

The carnage took place on Bedford Avenue near North Eighth Street, a block crowded with people enjoying the neighborhood’s ­vibrant bar scene.

One of the revelers was Batka, who had been drinking with other cops at a nearby bar, according to sources, who said he had a bar receipt in his pocket.

The three critically injured victims, all of whom are expected to survive, are a 24-year-old man at New York Presbyterian/Weill Cornell Hospital and a 20-year-old woman and a 23-year-old woman at Bellevue, according to the court papers.

Three of them had attended MIT, the other NYU. Their names were withheld pending family notification.

Batka, who was suspended from his job, “was really wasted,” said witness Kate Hanley. “When they brought him out, he was conscious but like someone that was blackout drunk. Four people had to get him out of the car.

“I heard people screaming and saw people lying all over the place. Just covered in blood and really badly ­injured,” she added. “Someone in front of my stoop had a bone sticking out of his leg. People were screaming.”

Neighbor Agata Winter heard people “screaming in agony — ‘Help!’ ‘God!’ I knew something terrible had happened.”

Angela Zielinski rushed over to help one of the victims, a woman.

“Her head, her leg were bleeding. She was squirming and squealing,’’ she said, adding that a man was impaled on a fence.

She told the driver, “Dude, what the f- -k. You just hit four people.’’ He stared back her “blankly.’’

At one point she saw Batka display his police badge to people gathered around his car.

Javier Alvarado, who works at a nearby market, pulled a woman out from under the vehicle. “I saw the girl with her leg broken, bleeding,’’ he said. “One guy took his shirt off and used it to try to stop the bleeding. She was conscious, she was very young.”

Batka refused to take a Breathalyzer, but a blood sample was obtained when he was brought to Weill Cornell for an examination. He was released to cops who busted him for crimes including manslaughter.

He was arraigned early Sunday in Brooklyn night court, where Judge Sharon Hudson set bail at $300,000.

Assistant DA Adam Wolk had asked for $1 million, saying that Batka tried to get away, that he moved to the passenger seat and claimed he hadn’t been driving.

Prosecutors said Batka was sitting in the SUV’s front passenger seat when cops arrived.

Batka had “bloodshot watery eyes, slurred speech, and the odor of alcohol” on his breath, according to the criminal complaint against him.

Defense lawyer Jeff Groden sought $250,000, noting that Batka lived with his family and is in the process of adopting the 15-year-old daughter of his recently deceased brother.

He posted bond and was released. He’s due back in court on July 21.

Batka’s Facebook page features more than a half-dozen photos of him posing with beer and booze. One of them, from 2013, shows him leaning over eight shots of booze, with the quip: “And all for me ;p.” He added: “it deff was a night to celebrate.”

A picture with the profile says: “Just because it’s a bad idea doesn’t mean it’s not going to be a good time.”

Batka, a former correction officer who worked with the Transit Bureau Manhattan Task Force, had attended John Jay College of Criminal Justice, his Facebook profile says.

Additional reporting by Audrey Williams, Jennifer Bain, Abigail Gepner, Brooke Baitinger, Jane Bealer, Leonica Valentine and Olga Ginzburg