NEW YORK -- The NYPD said late Thursday that MMA fighter Conor McGregor is in custody after video footage appears to show the promotion's biggest star throwing a guard rail at a bus full of fighters, injuring at least one scheduled to compete Saturday. He appeared to be involved in a backstage melee after a news conference for UFC 223, video showed McGregor with a group of people causing chaos Thursday as they took an elevator to the loading dock at Barclays Center in Brooklyn.

He can be seen tossing trash cans and being prevented from throwing a barricade at a bus during his unannounced appearance in New York.

The incident was posted on social media:

Conor McGregor. Picks up guard rail. Attempts to throw it at bus. ABSOLUTE CHAOS IN NEW YORK. #UFC223 (Via Felice Herrig's IG story) pic.twitter.com/JYQZD7jtKP — Chamatkar Sandhu (@SandhuMMA) April 5, 2018

After Thursday's incident, UFC president Dana White said a warrant was out for McGregor's arrest.

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"They are looking for him right now. His plane cannot take off; he cannot leave the state of New York," White said, according to ESPN. "I'm assuming, eventually, if they don't catch him, he'll turn himself in. You can imagine he's going to be sued beyond belief, and this was a real bad career move for him.

"After this disgusting, despicable move, I think everyone's relationship with Conor is going to be not so great," White continued. "Even the police officer who came to me was like 'God, I was a fan of his, too. Not anymore.' This is the type of bad move you make that turns a lot of people off."

CBS Sports writes that New York police are investigating and that no formal arrest warrant had been issued.

NYPD said Thursday evening it wants to question McGregor. A police spokesman said McGregor threw a hand truck at a bus causing minor injury to an individual on the bus.

McGregor hasn't fought for UFC since November 2016 and was stripped this week by White of the 155-pound championship he had never defended. White also said this week he did not expect McGregor to attend Saturday's UFC 223 card.

McGregor profanely responded on Twitter and wrote, "You'll strip me of nothing."

McGregor is tight with UFC 223 fighter Artem Lobov, who was involved this week in a scuffle in a hotel with Khabib Nurmagomedov. Nurmagomedov fights Max Holloway for the lightweight championship left vacant by McGregor.

Lobov was yanked from the card and the fight status of Michael Chiesa was unclear after he was sent to the hospital with injuries sustained in the attack.

The 29-year-old McGregor once held the 145 and 155-pound championships at the same time and boldly stated he wanted an ownership stake in UFC. But the trash-talking, egocentric has been out of the fight game except for his boxing dalliance with Mayweather that made him wealthy enough to never have to fight again. McGregor and his girlfriend welcomed their first child, a son, in May 2017.