All the victims were alive when transported to various hospitals, deputy fire chief James Mungovan said.
CNN affiliate WLS-TV reported four of the victims were in critical condition.
The shooting was reported about 10:15 p.m. in the Back of the Yards neighborhood. Police had taped off an outdoor basketball court there.
No suspects were in custody late Thursday. A police spokesman said investigators believe the shooting was gang-related.
Gun violence in Chicago was spotlighted in a February speech there by President Obama. The president, whose home is in Chicago, spoke about the shooting death of 15-year-old Hadiya Pendleton just a week after she took part in his inauguration ceremony in January.
The FBI’s annual crime report this week showed Chicago had 500 homicides in 2012, up from 431 in 2011 and more than any other American city. Chicago officials have said homicides this year are below the 2012 pace.