The investigation into a triple shooting Wednesday night at Eisenhower Park that left one teen dead and two others in critical condition continues today.

On Thursday afternoon, a 17-year-old, who News 12 is not identifying because of his age, pleaded not guilty to a criminal possession of a weapon charge.

In court, prosecutors said Nassau County police saw the Westbury teen at the park attempting to leave before he entered a gated area where a loaded high-capacity 9mm handgun was recovered.

Prosecutors said two 9mm shell casings were found at the scene, but the teen has not been charged in connection with the shooting.

His attorney and family denied that the teen did any wrongdoing.

On Wednesday night, Nassau County Police Commissioner Patrick Ryder said police arrested two people who both had weapons on them. Investigators have not yet identified who that second person is.

Nassau County police said officers responded to Eisenhower Park Parking Field Two around 8:30 p.m. Wednesday after receiving multiple calls for shots fired.

Investigators said a 15-year-old boy was taken to the hospital with a gunshot wound, where he died. Two other men, ages 28 and 31, also sustained gunshot wounds and are in critical condition.

Nassau County police have not provided any additional identifying information on the victims.

Ryder said the shooting happened after a group of people had gathered at the park for a "so-called barbecue" for members of the Bloods gang after invitations were spread on social media.

Two people got into an argument, which sparked the shooting, investigators said. Police have not described the nature of the fight.

Nassau County police have not said whether the shooter is in custody and how many people actually fired weapons.

News 12 reached out to Nassau County police again this morning after making multiple attempts to speak with Ryder on Thursday, but he was not made available.