Police said it happened in the Belmont Cragin neighborhood's 2100 block of North Meade Avenue just after 12:45 p.m.
A 26-year-old man was inside his home when someone entered without permission, police said. The victim fired at the offender, striking him twice in the chest.
Neighbors described hearing four to five gunshots before police came swarming the street.
The offender fled, but was found nearby. Neighbors told ABC7 that they saw a man, who looked to be injured, being treated on a stretcher.
The alleged invader was transported to Loyola Hospital in serious condition.
Neighbors said a family with children lives in that home, and police said no other injuries were reported.
Area Detectives are investigating and charges are pending.
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