Chicago police detectives are warning Northwest Side residents of a trio of robbers targeting people in garages and alleys.

The three men have committed at least seven robberies since Friday in the late afternoon and evening, according to a community alert issued by Grand Central Area detectives.

Victims were in open garages or alleys and were robbed at gunpoint of items such as wallets, money and cell phones, according to police.

In one of the robberies, the robbers may have fled in a vehicle described as a white or gray Nissan. In another robbery, they got away in a gray, four-door vehicle. The first robbery took place Friday in the 2200 block of West Fullerton Avenue at 7:53 p.m., followed almost immediately by one in the 2200 block of West Medill Avenue, a block away.

The robbers struck five times on Sunday, according to police. At 4:55 p.m., they robbed someone in the 3900 block of North Troy Avenue;  in the 3700 block of West Montrose Avenue at 5:15 p.m.; in the 6200 block of North Leona Avenue at 5:55 p.m.; in the 2400 block of North Maplewood Avenue at 6 p.m.; and finally, in the 2100 block of North Monitor Avenue at 9:05 p.m.

Police did not release detailed descriptions on the three individual robbers. However, the three were described as black men between the ages of 20 and 35, between 5-foot-7 and 6-foot-2, and weighing between 160 and 190 pounds. Each was wearing a different-colored baseball cap, and at least one of them had a handgun.

Anyone with information on the robberies is asked to call Grand Central Area detectives at 312-746-8362.