A 58-year-old man was fatally struck by a train on the Upper West Side this morning. Victim John Williams was struck by a southbound D train at the subway station at West 72nd Street and Central Park West around 6:45 a.m. Williams was taken to St. Luke's Hospital where he was pronounced DOA. Police told CBS that the man had climbed down onto the tracks to retrieve something when he was struck by the train.

MTA officials tell us the D was running local early this morning. Police add that Williams lives at West 175th Street; it's unclear how he ended up on the tracks, and cops are still investigating the incident.

This is the fourth subway-related incident in the last three days. A man was fatally struck by a northbound E train at 7th Avenue and 53rd Street in Manhattan around 7:45 p.m. Thursday night. FDNY adds that he apparently jumped in front of the train, and died at the scene. A 56-year-old person was struck by a train around 1:30 a.m. Friday at Fulton Street and Ralph Avenue; that person was taken to Kings County Hospital, but his or her condition is not known.

And on Thursday morning, a 23-year-old Florida man was fatally struck by a train. Cops believe that Bobby Legrand Guin, who had recently moved to NYC, had dropped a wad of $50 and $20 bills onto the tracks and had jumped down to retrieve them when he was struck by a northbound local A train. Friends have now set up a memorial for Guin at the station.