Philadelphia and Temple University police are warning students after a recent, " series of off-campus robberies" of students in the northwestern area outside campus on Sunday and Monday.

Philadelphia Police Central Detective Division and Temple are investigating the armed robberies, but have not said how many students were involved. Smart phones and purses draw thieves they said.

Ray Betzner, a Temple spokesman, said that the university made a decision to issue an advisory after Philadelphia police shared information on the incidents.

"We did it because it became apparent Monday - after receiving information from the Philadelphia Police - that there might be a pattern, that it goes beyond random acts," Betzner said.

In addition, Betzner said authorities also hoped it might prompt students with more information about the robberies to come forward.

Police from both departments are increasing patrols in that area and telling students to, "trust your instincts," according to the advisory. They are asking students not to walk alone, to stop using mobile phones and other devices in public, not talk to strangers, avoid dark or hidden walkways, and quickly leave places or situations that make them feel uncomfortable.

They also remind students to use the Owloop service for on-campus transport, and TUr Door service for those living off-campus. Both operate from 5:30 p.m. to 6 a.m.

Police gave the following times of the incidents and descriptions of the suspected thieves:

-At 8:45 a.m. Sunday, at 2000 N. 18th Street, a 30-year-old, black male, about 5'9", and wearing a black "beanie" cap, blue puffy coat and blue jeans was suspected of a robbery.

-At 8:15 p.m. Sunday, at Edgley Street, a black male with a red hoodie covering his face was suspected of a robbery.

-At 6 p.m. Monday, at 2100 N. 16th Street, a black male, about 6'1", with thin build, and wearing a black "hoodie" with baggy black jeans was suspected of a robbery.

Police ask students to call 911 if they spot trouble, or contact Temple Police by calling 1-1234 from a campus phone, or 215-204-1234 from a non-campus phone.