CHICAGO (CBS) — Chicago police were warning people on the North Side about a recent string of violent robberies in Ravenswood and Uptown.

Police said a group of at least three robbers approached the victims on the street, punched and kicked them without provocation, knocked them to the ground, and then stole their property.

Two of the robberies happened on March 7; one at about 1:10 a.m. in the 2500 block of West Lawrence Avenue, and the other at about 8:30 p.m. in the 4500 block of North Magnolia Avenue. Another robbery happened at 5:30 a.m. March 11, in the 4500 block of North Broadway.

Police did not have a detailed description of the suspects.

Area North Detectives were investigating. No one was in custody Monday morning.