Shantel McCoy, 32, died in the blaze. The fire broke at approximately 2 a.m. Sunday on the 12th floor of the 21-floor building.
Authorities say McCoy died after she returned home with a bag of food and got into an elevator to go to her 12th floor apartment, unaware fire had engulfed the floor.
When the elevator door opened, she was hit with 1,500-degree gas and fire fumes and killed.
The victim was found in the open elevator on the 12th floor.
Neighbors described a dramatic scene as firefighters tried to save people on the upper floors. Seven residents were injured. The two firefighters were treated and released.
"I did see flames coming out of the front of the building here and saw smoke pouring out of the rear of the building. [It was] a horrible, horrible thing," witness Brent Brooks said.
"It was scary. It was the middle of the night. We didn't have any idea what was going on, and when I saw the smoke outside our door, I didn't know if I was going to get out of that building," resident John Lapiana said.
The conditions of the residents injured range from critical to fair. The two firefighters that were injured are expected to be OK.
The Sunday morning blaze started in a unit on the 12th floor.
The occupants tell officials they were awakened by an apartment smoke detector, then saw their living room on fire. They got out.
But the door of the unit didn't close, allowing the flames to spread.
"There was smoke coming into the room so I grabbed what I could and headed for the stairwell," said resident Erin Teater. "I got down a couple of flights and couldn't see and couldn't breathe and someone started screaming to run back up."
As the clean-up began so did the investigation into what caused the fatal fire.
Fire investigators say the building does have smoke detectors in the units and hallways but no central alarm system or sprinklers.
A previously passed city ordinance requiring fire safety upgrades in building built prior to 1975 to be completed by this month was put off until 2015.
Residents whose homes were not damaged were allowed back into the building later Sunday morning.
The American Red Cross responded to the scene to help those residents who were displaced by the fire.
Chicago was supposed to be an exciting new beginning for McCoy, relatives said.
McCoy worked for Wirtz Beverage Group. The Philadelphia native moved here last March after she was laid off from her job at an accounting firm back home.
"Everybody is shocked because she was so young and outgoing and friendly, and everybody knew her," said the victim's uncle, Arthur McCoy. "She's the first person in our family to earn a master's degree. She was just a really outgoing person. She was career-minded."