Suffolk County Police have arrested a woman Wednesday for causing a hit-and-run crash that killed an 11-year-old girl.

Police say Maureen Lambert, 20, of Stony Brook was the driver who mowed down young Courtney Sipes as she was crossing the street with her mother and brother in Smithtown.

They tracked down Lambert by collecting eyewitness accounts and combing through surveillance videos near the scene.

Lambert turned herself in after police spoke to her family and convinced her to go to the precinct.

Lambert was charged with leaving the scene of a motor vehicle crash.

She was held overnight at the Fourth Precinct in Hauppauge Wednesday and is scheduled to be arraigned Thursday morning at First District Court in Central Islip.

"I feel really bad about it and I didn't mean to run away," Lambert told PIX News.

Courtney was crossing the street in front of 27 East Main Street with her family to a coronet music lesson at about 7 p.m. when a white vehicle, allegedly belonging to Lambert, barreled towards them and struck the girl.

Courtney's body was flung across the street and landed underneath a parked vehicle.

She was rushed to nearby St. Catherine of Siena Hospital, where she was pronounced dead.

Courtney was a fifth grader at The Pines Elementary School.

"She was an energetic, well-liked student who was involved with student council, was involved with playing the trumpet and involved with many other student activities," said a staffer at the elementary school.