The victims included a man who was coming to the aid of his girlfriend in Crown Heights, Brooklyn.
The 31-year-old man was shot in the torso outside 1316 Saint Johns Place just after 11:30 p.m.
He had been called there by his girlfriend, who was in a dispute with another man who had grabbed her.
Police say when the victim arrived, he was shot by the other man, who then fled the scene.
The victim was pronounced dead at Interfaith Hospital. No arrest were immediately made.
In other homicides, a 24-year-old man was shot in the chest at about 4:20 p.m. in Crown Heights and later died. And 23-year-old Johnson Sanchez was shot in the head at 1010 Hoe Avenue in the Bronx died at Lincoln Hospital.
Two other men were also shot in Brooklyn, but their wounds were not deemed life-threatening.
Finally, another man was shot in Manhattan and still another in Queens. Both were expected to survive.
Police were investigating all the incidents.