By Dan Wing and Tim Jimenez

PHILADELPHIA (CBS) — A hit-and-run driver who authorities say hit a Philadelphia Police Sergeant during a traffic stop has been arrested, thanks to a Good Samartian who helped police find him.

Colin Murphy, of Schwenksville was charged with Aggravated Assault While DUI, Criminal Mischief, DUI and other related offenses.

Investigators say Murphy hit 55-year-old Sergeant Joseph Cain Jr. so hard that the impact threw the officer 15 feet, and knocked him out of his shoes. Cain is a 26-year veteran of the department.

Police say the Sergeant and another officer had stopped a vehicle on Main Street near Shurs Lane around 1 a.m. when the Sergeant was struck.

He was taken to Einstein Medical Center where he was treated for a broken collarbone and various bruises. He is listed in stable condition.

Police say the driver kept going but a tow truck driver who saw what happened followed the SUV and called police.

Officers stopped the driver a mile away. Chief Inspector Scott Small says it appears he had been drinking, “maybe here in Manayunk.”

(credit: CBS3)

(credit: CBS3)

“5th District officers were able to stop the Toyota about a mile away on the 6000 block of Ridge Avenue. The driver of the vehicle who hit the Sergeant is a 21-year-old male. He did appear to be under the influence of alcohol, so he was taken into custody, and he will be transported to police headquarters where he is going to be processed for drunk driving.”