A fiery, four-vehicle crash involving a stolen car on Long Island left five people dead Wednesday, Suffolk County ­police said.

Cops using OnStar were tracking the stolen car, a 2018 Chevy Camaro, which was speeding eastbound when it rear-ended a 2012 Mazda carrying four people and then hit a home-heating-oil truck at about 11:20 a.m. on Route 25 near Woodlot Road in Ridge, authorities said.

The Mazda burst into flames, killing its four occupants, and struck a 1999 Infiniti, whose driver appeared not to be seriously injured, cops said.

“This morning I came out to go shopping, and I turn the corner and there’s a car in flames right in front of me,” said Loretta Burns, 62, who lives on Woodlot Road.

“I got out and ran over and one policeman was trying to open the door. The flames were just too much for him.”

The force of the crash ejected one occupant of the stolen ­Camaro, identified by relatives as 19-year-old Londell Skinner, who died. A second occupant, and the truck driver, were taken to Stony Brook Hospital with non-life-threatening injuries.

Suffolk County cops were alerted to the stolen car at 11:15 by OnStar, and tracked it to an apartment complex about a mile from the crash scene.

“The officers responding believed they had the car contained but the car drove over the grass traveling east on 25 at a high rate of speed,” said Suffolk County Chief of Department Stuart Cameron.

The cops followed the Camaro from “some distance” behind, he said. The three cars involved were heading east at the time of the crash, while the oil truck was traveling west.

“The road undulates so the officer didn’t actually see the accident. But that is subject to this investigation. At this point it is not a police pursuit,” Cameron said.

“It appears as though the 2018 Camaro struck a 2012 Mazda and a residential-oil-delivery truck.”

Burns said that afterward, a deeply distressed young woman in the Infiniti said she had been rear-ended in the crash, which left large pieces of debris strewn about the highway.

“She got hit from behind hard,” Burns said. “She was crying hysterically.”

Skinner’s mom wailed in grief at the scene, breaking through police tape as she ran toward the wrecked cars, witnesses said.

“No, no, my son,” she shouted. “He’s dead, he’s dead.”

Additional reporting by Stephanie Pagones