Investigators say the fire started accidentally.
It happened in the 1200- block of Valley Lake Drive. Hundreds of people were displaced during the clean-up.
"It was full of smoke, and the entire lobby was full of smoke," said resident Prabu Thorali. "There was zero visibility"
Some 140 families rushed out quickly.
"I was sleeping and I suddenly hear the fire alarms started ringing," said resident Shirshir Rao.
Smoke was coming from a bedroom in a fourth floor unit.
"The firefighters were able to quickly find that, got that water on it quickly and kept it contained really to the room within the apartment," Schaumburg Fire Department Capt. John Steele.
Two roommates who live across the hall from where the fire started, helped save an elderly woman inside.
"We woke up and heard some voice and saw that old lady come from the house and saying fire, fire please help," Thorali said.
That 85-year-old woman was rushed to a hospital with life-threatening injuries.
Investigators say the fire may have been started by a candle or possibly something electrical.
To make matters worse-, there was a water main break that shut water off to the building.
It caused flooding on the lower floor, which left residents outside in the cold.
"I don't know, we'll have to figure out what to do later," Rao said.
After several hours, residents were escorted inside briefly to gather any needed belongings from their units and the Red Cross is helping them find a place to stay.