One man is dead and 11 others are injured after a late night shooting in Brooklyn.

The shooting erupted just as the crowd at the annual Old Timers Event in the Brownsville neighborhood was beginning to disperse Saturday, witnesses said.

“There were a lot of people just chilling and having a good time,” Kaseem Collins, 19, told the Daily News. Then, when shots rang out, “we all started running,” he said. “I ran as fast as I could away from everyone. I thought I was going to get shot.”

“I heard shots, and I saw a stampede running toward me,” Diamond Perez, 38, told the newspaper.

NYPD Commissioner James P. O’Neill told NY1 that police do not have a suspect and that it’s unknown whether there was more than one gunman. He said 12 people were shot, but that it wasn’t clear what led to the gunfire.

A 38-year-old man died with a single bullet wound to his head, a New York City police spokesman said. His identity was not released.

O’Neill said six of the wounded have been released from the hospital. He did not address the conditions of the five others. Hours earlier, a New York City fire department spokesman said some were in serious condition.

The police commissioner said 2,000 to 3,000 people were attending the event next to a playground, and that more than 100 police officers were stationed there.

A 2010 newsletter from the parks department described the Old Timers Event as a celebration of former members of the Brownsville Recreation Center “who went on to success and fame in sports and other endeavors.” It said the event has grown over the years to include concerts and other things.

Mayor Bill de Blasio tweeted early Sunday that the shooting “shattered a peaceful neighborhood event.”

“One of the worst experiences of my life,” City Council member Alicka Amprey-Samuel tweeted. “How does such a beautiful and peaceful event become overshadowed by tragedy in seconds?”

“It was chaos,” Gary Miller, a 60-year-old vendor at the event, told the New York Post. “Shots rang out and the crowd was already dispersing and you heard about 9 to 11 shots and everyone was running and scattering for cover.”

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.By mid-morning, the area was cordoned off with police tape. Plenty of litter was strewn about the ground.

Brownsville is an east Brooklyn 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.

De Blasio and O’Neill are holding a news conference about Saturday’s shooting. Brooklyn community leaders, including Public Advocate Jumaane Williams and Brooklyn Borough President Eric Adams, are attending the conference as well.

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.”