The stabbing happened shortly before 1:30 Sunday afternoon. An eyewitness says the victim was standing on the sidewalk near Central Park South, when a man, who appeared to be homeless walked up and attacked him for no apparent reason.
"The guy came behind him and hit him with a Swiss knife. After that we saw the guy bleeding from his back," the eyewitness said.
The attacker fled the scene. Police say the 23-year-old victim was stabbed in the torso. He was taken to the hospital where he is expected to survive.