The Metropolitan Transportation Authority conductor was sitting on a bench at the southbound platform for No. 2, 4 and 5 trains at 149th Street and Grand Concourse in the Bronx when the suspect randomly approached him and slapped him in the face, MTA worker Tina Smith told ABC New York station WABC.
The pair then engaged in a physical fight, and the suspect stabbed the MTA worker several times in the shoulder and torso, WABC reported. The 33-year-old conductor was able to hold the suspect, identified as 20-year-old Walter Rivera, down until police arrived and took him into custody.
Rivera was charged with assault and criminal possession of a weapon, according to WABC.
The conductor was in uniform when he was attacked, photos posted by WABC show.
Smith said the suspect was "looking for trouble."
"Why would you have a knife if you weren't looking for trouble?" Smith told WABC.
An image tweeted by WABC reporter Kemberly Richardson shows the MTA worker being treated for a gaping gash on his upper back. Another photo shows a large knife lying on the platform ground.
The conductor, who has been on the job for five years, was taken to a local hospital for non-life threatening injuries, according to WABC.
Additional details were not immediately available.