An underage driver doing 51 mph in a 30 mph zone on the Bruckner expressway last night flipped his family's GMC Envoy and killed his 12-year-old front seat passenger, police sources say. The victim, a Bronx girl identified as Kaitlin Booth, was rushed Jacobi Hospital, where she died. The name of the 15-year-old driver hasn't been released, but investigators believe the accident happened after the vehicle jumped a curb, tore through a chain-link fence, crashed into a tree stump, and flipped on its side.

The Post and the Daily News have conflicting reports. According to the News, a 15-year-old boy told cops on the scene that Kaitlin was walking on the sidewalk when the SUV mowed her down, and the boy also claimed that men ran from the vehicle after the crash. But sources tell the Post that the 15-year-old boy, who suffered facial injuries, was driving, with Booth as his passenger. No charges have been filed yet.