Arlington Heights police and fire crews responded just before 7:30 p.m. to a BP gas station in the 2200-block of South Arlington Heights Road for a report of a man with a knife and a man stabbed in the chest.
The man who was stabbed was critically injured and taken to a local hospital, where he stabilized, police said.
A second person was also cut and hospitalized, but he has since been released.
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Several people left the scene of the stabbing before officers arrived, police said, and the suspect is not in custody.
However, he does not pose a current threat to the public, according to police.
This appears to be an isolated incident.
The incident spurred a large police and fire response, and officers are processing multiple crime scenes.