Excerpts from Chicago.cbslocal.com:

A Chicago firefighter was injured during a rescue of a resident from a blaze on the South Side Saturday. The firefighter was being treated at University of Chicago Medical Center and is in serious to critical condition. A witness said he appeared to be overcome by smoke while entering the home.  Firefighters on the scene indicated he should be OK.

Three people, including a woman rescued from the second floor of the home, were sent to Jackson Park hospital. Their injuries were not believed to be serious.

The fire happened on the first floor of the home in the 8700 block of South Constance Avenue in the Calumet Heights neighborhood around 12:30 p.m. Fire department officials say the firefighter was injured trying to save an elderly woman trapped on the second floor.

The cause of the fire, which was extinguished about an hour, is not known at this time.