It happened around 1:15 a.m. on Sunday, July 19 in Plainview.
Several shots were fired into the large crowd at the party, which was held in the backyard of a residence on Maxine Avenue, Nassau County Police said.
An adult male victim was struck in the leg and transported to a nearby hospital for the treatment of non-life-threatening injuries, according to police.
The investigation is ongoing.
Detectives request anyone with information call the Second Squad at 516-572-6253 or Crime Stoppers at 1-800-244-TIPS.
All callers will remain anonymous.
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