A 23-year-old man told officers he was stabbed in the left arm by someone in a large crowd just after 9 p.m., police said.
There was a visibly large police presence around the tiny park near Plymouth and Van Buren.
The victim was transported to Northwestern hospital in critical condition, according to police.
A knife was recovered at the scene, police said.
So far no arrests have been made.
The investigation into the stabbing remains ongoing.
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