The two off-duty NYPD cops who died in an upstate car crash Sunday night — after one had just gotten married — were speeding up and down a country road in a Maserati when they missed a turn and smashed into a tree, according to officials and witnesses.

Ulster County resident Gregory Zaff, 72, told The Post his wife heard the car’s screeching tires as it zoomed past their house several times — going back and forth to the Full Moon Resort, where the wedding reception had just taken place — before the collision.

“The road comes up and banks to the left, they lost contact and kept going straight off the right side of the road. They hit that big maple there, flipped in the air 75 to 100 feet [away] and landed upside down over here in the river,” said Zaff, 72, who ran out while his wife, Susie, called 911.

“It was terrible. I ran down and it was a four-door Maserati upside down, the entire roof was crushed.”

Inside the totalled black sports car, Officers Michael Colangelo, the 31-year-old newlywed, and John Martinez, 39, were clearly dead in the front seats — but Colangelo’s civilian pal Cody Kalina, 28, was still alive in the back seat.

When first responders arrived a few minutes later, a bloodied Kalina walked away from the crash and was flown to an Albany hospital with a head injury — where his mom told The Post he was “doing OK” Monday afternoon.

Meanwhile, Colangelo’s distraught family members arrived from the resort a mile away but were held behind a blockade of cars, Zaff said.

“The worst part was the groom’s father. They held him back about a block up the road here. He was screaming and banging on the cars like a madman for five or 10 minutes,” said Zaff.

“It was terrible to listen to him wail. They had to sedate him.”

At a press conference Monday afternoon, state police said it is still unclear if alcohol was involved. An irate wedding guest at the Full Moon told The Post, “They shouldn’t have been driving,” but wouldn’t say more.

Colangelo, a 10-year officer with the NYPD’s ESU K-9 unit, and Martinez, who worked at the 84th Precinct in Brooklyn, likely weren’t wearing seatbelts, while Kalina was, said Major Pierce Gallagher.

Gallagher said he believes the men were speeding and that Martinez, who’d rented the Maserati, was behind the wheel. The road they were on has a limit of 40 miles per hour, Gallagher said — although Zaff added that the narrow turn they missed is 20 miles per hour.

They seemed to be taking the car out for a spin after the wedding reception wrapped up, Gallagher added.

“As far as we can tell, they were taking this car out for a ride,” he said.

Colangelo’s new bride, Katherine Berger, is “grief-stricken,” Gallagher added.