NEW YORK, United States (AFP) — Irish Mixed Martial Arts fighter Conor McGregor was charged with assault and criminal mischief by New York police on Friday and was due to appear in court.

The 29-year-old superstar reportedly surrendered at a Brooklyn police station late Thursday after allegedly attacking a shuttle bus loaded with fellow mixed martial arts fighters attending a New York media event at the Barclays Center stadium.

Video footage showed McGregor hurling a dolly through a side window of the bus as it moved slowly in a parking lot at the stadium in Brooklyn.

Police confirmed that McGregor had been charged with three counts of assault and one count of criminal mischief, and that Cian Cowley, 25, another MMA fighter, had been charged with one count of assault and one count of criminal mischief.

The two men were to appear before a criminal court in Broodlyn, New York, on Friday.

Ultimate Fighting Championship President Dana White said fighter Michael Chiesa, who was on the bus, was taken to hospital following the incident and was being treated for cuts to the face.

Police had issued a warrant for the arrest of McGregor, White added, accusing the Irish star and a group of around 20 men of “storming the building.”

“They got down to the loading docks where the fighters were getting on the buses and attacked them, throwing trash cans, dollies, things like that,” White said. “Broke one of the windows, cut Michael Chiesa real bad, cut his hand, cut his face.”

White called it “the most disgusting thing that has ever happened in the history of the company,” and said “everyone’s shaken up.”

White warned that McGregor, who reportedly pocketed around $100 million for his superfight against boxer Floyd Mayweather last August, would face likely legal action.

“As you can imagine he’s going to be sued beyond belief,” White said. “This was a real bad career move for him.”

It was not clear what triggered the alleged assault but it appeared to be linked in part to the UFC’s decision to strip McGregor of his world title.

McGregor reportedly turned up unannounced at the end of Thursday’s press event to publicize the upcoming UFC 223 card.

On Wednesday, White said the UFC would strip McGregor of his lightweight title, which would be awarded to the winner of Saturday’s UFC 223 fight between Khabib Nurmagomedov and Max Holloway in New York.

McGregor reacted angrily to the decision on social media. “You’s’ll strip me of nothing …” McGregor said.