CHICAGO (CBS) — Chicago police are warning about a string of business burglaries on the city's Northwest Side.

At least seven burglaries were reported on Thursday. 

Police say three men, between 16 and 25 years old, have been using a hammer or crowbar to break the glass front doors of businesses before making off with cash, safes, and electronics.

Incident times and locations:

• 4700 West block of Belmont Avenue at 12:00 a.m.
• 4800 West block of Irving Park Road at 1:00 a.m.
• 5300 West block of Devon Avenue at 4:05 a.m.
• 5300 West block of Devon Avenue at 4:39 a.m.
• 5300 North block of Milwaukee Avenue at 4:48 a.m.
• 5600 West block of Montrose Avenue at 5:05 a.m.
• 3600 South block of Iron Street at 6:28 a.m.

Police said the burglars were wearing black masks, black hooded sweatshirts, black pants, and gloves.

Anyone with information is asked to contact the Bureau of Detectives – Area 5 at 312-746-7394.