Marshall, 26, turned himself in at the Glen Cove police station and is accused of shooting three people at the party, including a security guard.
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Marshall is facing attempted murder and weapons charges and is scheduled to be arraigned on Friday.
Gunfire erupted around 5 p.m. July 10 at the Mansion at Glen Cove, a swanky hotel on Long Island's Gold Coast, when police say the security guard tried to break up a fight between two partygoers.
Police described the scene as complete chaos, with between 150 and 200 people in attendance when the shots rang out.
The building serves as an event venue in addition to being a hotel, and police say it was a promoted party with a flyer posted and shared online.
The shooting happened near the front entrance of the lobby.
"It's a bit of a shock, yeah, it's a surprise," Glen Cove Mayor Pamela Panzenbeck said at the time of the shooting. "This is just a beautiful venue. It's used for high school reunions, weddings, fundraisers, for events, and things like this don't happen here."
All victims suffered non-life-threatening injuries and were treated and released from the hospital.
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Sources told Eyewitness News that the venue did not have the proper permit from City Hall to host an outdoor event.
Glen Cove police said an application was submitted, but the permit was never signed.
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