Ann Arbor police are investigating four robberies in the past 10 days, according to the University of Michigan Division of Public Safety and Security.
The latest robbery happened around 1 a.m.Sunday.
In that incident, a female student was talking in the area of Vaughn and east University streets, off central campus, when a man got out of a car and pulled a gun on her. He had a bandana over his face, demanded her backpack and took off in a vehicle.
Both the Ann Arbor police and Division of Public Safety and Security are using several strategies, including increasing patrols, to help stop the crimes.
Pedestrians are encouraged to walk in pairs or groups, and residents are asked to leave their porch lights on.
Anyone with information is asked to call Ann Arbor police.
