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.

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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.

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Police did not have a detailed description of the suspects.

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