The blaze erupted at 4:45 a.m. in an five-story apartment building at 915 W. Wilson. A third-floor resident was looking for something under his mattress with a lighter when the mattress caught fire, according to the fire department.
Residents were evacuated due to the smoke and at least one person was taken to the hospital for observation. That person is expected to be OK.
"We assisted several people out of the structure...that was our main concern," said Chief Thomas Kennedy, Chicago Fire Department.
"I was asleep and my neighbor, she come banging on my door and she woke me up. And it was really smoky...we couldn't go down the elevator," resident Dora Murphy said.
Firefighters were able to strike the fire shortly after arriving on the scene.
Fire alarms in the building were working. There was no structural damage.