A speeding underage driver, believed to be 15 years old, lost control of a stolen SUV on a Long Island highway causing it to crash and overturn — killing three teenagers Friday, police officials said.

The victims — who were ejected from the vehicle — were among 10 people, including an 8-month-old, who were crammed inside of a 2005 Chevy Trailblazer at the time of the horrific 11:45 a.m. crash on the Meadowbrook State Parkway near Merrick Road in Nassau County, authorities said.

The infant, whom police believe was restrained in a child car seat, and the six other teenagers, who are from Uniondale, suffered non-life threatening injuries and were taken to area hospitals.

“The infant is OK,” Major David Candelaria of the New York State Police said at the press briefing near the scene of the single-vehicle crash.

The Chevy Trailblazer, which was reported stolen Thursday out of Roosevelt, was spotted traveling southbound on the highway “at a high rate of speed and driving erratically,” weaving “in and out of traffic,” Candelaria said.

“The vehicle did lose control, overturned several times and came to final rest on the west shoulder into the marsh,” Candelaria added.

The teen driver survived the crash, police said. She is conscious and authorities were in the process of interviewing her.

Two of the teens who were killed were pronounced dead at the scene, while the other was pronounced dead at an area hospital.

The teens inside the vehicle ranged in age from 13 to 18, Candelaria said, noting that not everyone was wearing a seatbelt.

The vehicle, Candelaria said, traveled several hundred feet from the beginning of when the driver started losing control before coming to a stop.

“It’s quite a distance,” he said.

A witness who was traveling in the same direction told cops “the vehicle came up behind me at a high rate of speed and swerved around me.”

“So our collision reconstruction unit will investigate the collision and determine causation, speed, things of that nature,” Candelaria said.

He added that the vehicle “kind of veered to the left” and the driver “over-corrected and then the vehicle overturned several times coming to final rest into the west shoulder marsh.”

The SUV was not being pursued by authorities at the time of the crash and there was no indication that it was racing without another car, Candelaria said. It was not known where they were headed.

There were no immediate signs of drugs or alcohol.

Additional information about the victims was not immediately available.

Three victims under the age of 18 were taken to Cohen Children’s Medical Center, while the others were taken to another area hospital.

The New York State Bureau of Criminal Investigation along with its Collision Reconstruction Unit, Forensic Identification Unit, the Nassau District Attorney’s Office and the Nassau County Police are investigating the crash.