The incident happened after 9:30 a.m. on Montgomery Street near West Side Ave.
Baseball head coach Sean Cashman was transported to the hospital after a possible robbery attempt inside the parking garage.
Cashman is at Jersey City Medical Center in stable condition.
Police fanned out across the neighborhood asking if anyone had seen or heard anything. The garage sits across from several homes and businesses. A security guard apparently broke up the robbery and chased the suspect.
"This has never happened, it's a safe campus. It is safe, and thanks to the quick thinking of security, she thwarted the robbery and we're happy about that," said Sarah Malinoski-Ferrary with St. Peter's.
The guard explained to police what happened, how she intervened chasing the robber away, but not before he fired off one round, shooting the 25-year-old university employee in the leg as he was leaving his car.
The school sent alerts to students.
Security has been out in force around the campus forces on bikes and at corners. The suspect ran off down west side avenue where, students say they've known of problems before.
Anyone with information is asked to call the tip line at 201-547-JAIL.
