AP - A gunman who had just fatally shot a man in a New York apartment hopped on a packed city bus Friday -- where shortly afterward he murdered another man and shot a third victim, police said. "I had to settle a beef," the man allegedly told police after they nabbed him seconds after he ran from the panic-stricken Q111 bus in the Jamaica section of Queens. The mayhem began at 3:41pm in South Jamaica, in a second-floor apartment at 163-11 Foch Boulevard. The unidentified gunman shot an 18-year-old man in the neck inside the apartment, police said. The victim then leaped from the window and fell to the ground below. The wounded man then managed to stumble to the nearby Royal Chicken restaurant, where workers called 911, but he was dead by the time he was taken to Jamaica Hospital, authorities said. In the meantime, the shooter had fled the apartment to the street below. He ran a short distance to nearby Guy R. Brewer Boulevard, where he jumped onto a northbound Q111 bus. Officers responding to the 911 call went to the apartment where the shooting occurred -- and immediately found an ID that the gunman had accidentally dropped when he fled, police said. Twenty minutes later, at 4:04pm, the gunman got into a dispute with at least one other passenger about the jammed Q111 as it pulled into the major transit hub in downtown Jamaica transit hub on Archer Boulevard.The killer pulled out a 9mm Ruger semi-automatic pistol and began firing -- hitting two men. One of those men died on the bus. The other victim, managed to get off the bus and ended up sprawled on the sidewalk, as terrified fellow passengers fled. He later was taken to Jamaica Hospital, where he was in stable condition, authorities said. Among the people fleeing the bus was the gunman, but he didn't get very far as he was quickly nabbed by cops racing to the scene. Officers found the Ruger pistol on him. The gunman was being questioned further at the 103rd Precinct.