"Careless discarding of smoking material" was the cause of the fire, CFD said.
CHICAGO (WLS) -- Two people were injured in a fire at a high-rise on the city's North Side, sources told ABC7.
The fire happened at about 6:49 a.m. at a high-rise building at State and Maple streets in the city's Near North neighborhood.
Chopper 7 was over the scene at 7 a.m. showing the large response from the Chicago Fire Department.
Two people were taken to the hospital, one person was in serious condition while the other is expected to be okay, sources said.
The fire was contained to unit on the 15th floor of a 52-floor building.
CFD said an investigation found that "careless discarding of smoking material" was the cause of the fire.
Kevin Smith, who is visiting from Holland, Michigan, witnessed as flames engulfed the single unit.
"Big flames in the one room and then it looked like it spread a little bit and then smoke was coming out," Smith said.
Chopper7 was over the scene showing the scale of the large firefighter response.
Fire trucks and ambulances lined State Street from Oak to Cedar streets as firefighters worked to secure the building.
"Everyone was coming up out of the trucks and going in. All of a sudden you could see the flames start to die down. Their reaction time was incredible," Smith said.
"I came down actually I forgot my keys," said Jake Lamb, who lives in the building. "I was getting a spare key from the desk and whenever I tried to go back up, all the elevators had shut down."