University of Michigan police are urging residents on North Campus to lock their sliding glass doors after four apartments had items stolen during break-ins during the past month.

The Department of Public Safety issued a crime alert Tuesday after two apartments on McIntyre Road were reportedly broken into, according to police.

The first incident occurred at 4 a.m. Tuesday at an apartment in the 1500 block of McIntyre Road and the second break-in occurred at about 8 a.m. at an apartment in the 1100 block of McIntyre Road, according to police.

Two apartments on Stone Road were reportedly broken into on March 2 during the nighttime hours, police said. Backpacks were stolen from both of the apartments while the residents were sleeping, police said. The intruder, or intruders, entered the apartments through unlocked glass sliding doors on the first floor.

The sliding glass door at the apartment in the 1500 block of McIntyre Road was also unlocked when an intruder opened it, police said. The resident reported waking up and seeing a person opening the door before running away from the apartment. It’s unknown if the person actually entered the residence.

The resident of the second apartment reported a backpack and jackets were missing from the living room. He told police the sliding glass door was still open and was unlocked and he found the backpack and jackets outside the apartment nearby, police said.

Anyone with information on these incidents is encouraged to call police at 734-763-1131.

Kyle Feldscher covers cops and courts for AnnArbor.com. He can be reached at kylefeldscher@annarbor.com or you can follow him on Twitter.