Police are investigating the shooting at Eisenhower Park in East Meadow as gang-related. It happened around 8:30 p.m. Wednesday.
A 15-year-old boy died. Two other men, 28 and 31, were also shot and taken to a hospital where they are in critical condition.
A 17-year-old is charged as a juvenile in the case and is being held as the investigation continues. Sources tell Eyewitness News the teen is being eyed as the shooter.
Authorities say it happened at a barbecue designed to attract members of the Bloods gang, an event advertised on social media.
Police say when people showed up for the so-called barbecue, an argument broke out between two people and shots were fired.
Officials say they will not tolerate any gang activity in Nassau County.
"We will not tolerate gang activity in this county, we're not going to tolerate what happened...it will be addressed, going forward there will be no more parties like this in the park," said Nassau County Police Commissioner Patrick Ryder.
Law enforcement said they recovered a gun in the park. Ballistics will determine how that weapon was used and the role of a second gun retrieved from someone else who is in custody, but not yet charged.
The investigation is ongoing.
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