NEW YORK (CBSNewYork) – A man was stabbed on the Upper West Side Thursday afternoon while trying to help two strangers in distress.

The incident began when a man and his son were walking on 79th Street and Broadway at around 1:30 p.m.

Another person accosted the two, according to police.

A dispute broke out and a good Samaritan stepped in to help.

The suspect then stabbed the good Samaritan before running into Riverside Park.

As CBS2’s Valerie Castro reported, police were called to the scene where they found the suspect’s shirt. They brought in a K9 to try to track the suspect’s scent, but eventually lost the trail.

Upper West Side residents said it’s unnerving to see the large police presence in the park in the middle of the day.

“It just seems kind of scary, this is a pretty nice area, it’s very quiet, it’s even a little bit boring but I mean it’s scary,” David Epstein said.

“It’s unsettling, but I guess that’s the thing about New York, you’re one step away from danger all the time,” another resident said.

The good Samaritan was treated at the scene for a minor injury. He then came to the park to help police search for the suspect.

The suspect has not been found, and CBS2 has been told the man and child initially involved in the dispute left the area before police arrived.