One person died and 11 others were wounded in a shooting near a Brooklyn playground on Saturday night, police said.
New York police said Sunday that there were two shooters and two guns but no arrests have been made.
"We had a terrible shooting in Brownsville tonight that shattered a peaceful neighborhood event," New York Mayor Bill de Blasio tweeted soon after the incident.
"Our hearts go out to the victims," he added. "We will do everything in our power to keep this community safe and get guns off our streets."
NBC New York reported that it appeared the attack took place during an annual community event called Oldtimers Day. Though the festival was nearing its end, about 100 officers were still in the area when the shooting occurred, police said.
An unidentified 38-year-old man had died at an area hospital after being shot in the head. Another man is in critical condition, police said.
NBC New York reported that as many as 12 people were hit in the 11 p.m. shooting. Six of those injured were men and five were women, all ranging between 21 and 55 years old.
"We're still tallying up all the victims, unfortunately," said a police spokesman who did not provide his name.
Police asked that anyone present at the festival share photos and videos from before, during and after the shooting.