Chicago police say five people were shot, four killed, at an apartment building on the city's Northwest Side.
The Chicago Sun-Times reports the shooting happened around 5:30 p.m. Saturday. First Deputy Superintendent Anthony Riccio says a 67-year-old man with a history of issues with his neighbors is in custody.
Riccio says the man first went into an apartment and shot three men and a woman as they ate dinner. The man then went to a separate unit in the building and shot another woman. Police say one victim is in critical condition.
A weapon was recovered. Riccio says the man had a history of complaints from other residents but investigators "don't know what set him off."
Police say the victims were all adults, though their names have not been released.
An investigation is ongoing.