An Evanston Fire Department spokesperson said firefighters responded to a building in the 2600-block of Harrison Street around 6 p.m.
When crews arrived, they saw heavy smoke and flames coming from the building, and people were evacuating.
Chopper 7 was over the scene around 6:30 p.m. and captured video of crews working on the roof as smoke came out of windows.
1 person critically injured in fire at north suburban home: officials
Firefighters rescued a person from the building's second floor. That person, who suffered severe burns, was transported to a local hospital in critical condition.
No firefighters were injured.
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Two people were displaced, and the American Red Cross has been contacted to help the displaced residents by providing shelter and support services.
Residents can call or text 847-448-4311 for more information. Residents can also dial 3-1-1 in Evanston for assistance.