Gunfire at a large, outdoor event in Brooklyn killed one man and injured at least 11 others late Saturday night, police said.

Mayor Bill de Blasio tweeted early Sunday that the shooting in east Brooklyn’s Brownsville neighborhood “shattered a peaceful neighborhood event.” Twelve people were shot, including a 38-year-old man who was dead on arrival at a local hospital, a New York City police spokesman said around 3:30 a.m. Sunday.

The police spokesman said he did not know the identity of the man, who was shot once in the head.

No arrests have been made, and police did not offer details about a possible suspect or whether there was more than one gunman at the park where the event took place. As of 6:30 a.m., police said they did not have details about the conditions of the other 11 people wounded and that the investigation as ongoing.

At least six people had been transported to local hospitals by just after midnight, with some in serious condition, a New York City fire department spokesman said earlier. He described the scene at the time as “fluid.”

De Blasio’s tweet didn’t include details about the community event referenced, but a notice on the NYC Parks website said other programming at the Brownsville Recreation Center by the playground was canceled over the weekend because of the annual Old Timers Event.

A 2010 newsletter from the parks department described it as a celebration of “former members of the center who went on to success and fame in sports and other endeavors” that’s grown to include concerts and other events. A flyer for the dayslong celebration said Saturday’s event was to begin at 6 p.m. on Hegeman Avenue, in the vicinity of the site of the shooting.

Calls and emails to the offices of council members organizing the celebration were not immediately returned, but Council Member Alicka Amprey-Samuel shared de Blasio’s tweet and added comments of her own.

“One of the worst experiences of my life,” the council member for the 41st District tweeted. “How does such a beautiful and peaceful event become overshadowed by tragedy in seconds?”

A man who answered a phone number listed online for one of Saturday’s scheduled performers, The Legendary Intruders, identified himself as band member Khalil Shabazz. He told The Associated Press that his band had already performed and departed the venue by the time of the shooting.

Videos posted on social media showed police clearing large groups of people out of the area around the recreation center following the shooting. Photos from local news outlets showed several people taken from the scene on stretchers, including some with what appeared to be minor wounds.

Brownsville is a neighborhood that’s continued to struggle with gun violence, even as New York streets become safer than they have been in decades.

“We will do everything in our power to keep this community safe and get guns off our streets,” de Blasio tweeted.

State Sen. Roxanne J. Persaud echoed de Blasio, adding the hashtags ”#StopTheViolence” and ”#PutDownTheGuns” to her tweets expressing frustration with the shooting, which she called “unacceptable” and “cowardly.”

“Our community mourns again. We should be able to have fun in open spaces without fear of violence,” tweeted Persaud, whose district includes Brownsville. “Respect your community. We are better than the violence.”

(AP)