A 15-year-old driver was seriously injured in a three-vehicle crash in Central Islip on Wednesday after he took his mother's car keys without permission and went for a drive, Suffolk police said.

"Basically, his mom was at work and he managed to find the keys and went for a joy ride," Det. Lt. Matt Sullivan, the Third Squad commander, said.

The teen was still hospitalized in serious condition as of Thursday afternoon and he was expected to survive, Sullivan said.

State law requires a driver to be at least 16 years old to obtain a learner's permit.

Suffolk County police said the teen, whose identity was not released, was airlifted to Stony Brook University Hospital after the 3:11 p.m. crash with a National Grid truck and another car at the intersection of Brier Street and Route 111.

The boy was admitted to Stony Brook in serious condition.

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Police said one passenger, a girl, in the Honda the teen was driving was treated for minor injuries, as were three passengers in a 1998 Mazda, driven by a 32-year-old man.

The 34-year-old driver of the National Grid truck was not injured in the crash, police said.

Both the 15-year-old and his passenger are from Central Islip. Police did not immediately know how long they had the car or how many miles they had driven before the accident.

Police said the teenage driver was attempting to make a left turn from Brier onto southbound Route 111 when he collided with the northbound National Grid trick and then with the Mazda.

Police are asking any witnesses to call Third Squad detectives at 631-854-8352 or Crime Stoppers at 800-220-TIPS.

With Gary Dymski and John Valenti