CHICAGO (CBS) -- Four people were wounded in a shooting Monday afternoon in the South Shore neighborhood.

Police said four men were on the sidewalk in the 1600 block of East 79th Street shortly before 3:30 p.m., when someone walked up and started shooting.

Three victims were taken to University of Chicago Medical Center for treatment -- a 23-year-old man was in critical condition, a 32-year-old man was in critical condition with a gunshot wound to the chest, and a 31-year-old man was in good condition with a graze wound to the body.

A fourth victim, a 31-year-old man, was taken to Northwestern Memorial Hospital in fair condition, with a gunshot wound to the shoulder.

No one was in custody Monday afternoon.

Area Two detectives were investigating.