A 23-year-old man was discovered on a sidewalk overnight with a laceration to his arm after being attacked by a knife, Chicago police said.

Shortly after 9 p.m. Friday, the victim was in a large crowd in the 300 block of South Dearborn Street when someone attacked him with a knife before fleeing the scene, police said.

He was taking in critical condition to Northwestern Memorial Hospital. A knife was recovered near the scene.

No one was in custody and detectives were investigating.