UFC president Dana White said credentialed journalists from McGregor's website, The Mac Life, let McGregor and a large entourage into Barclays Center.

McGregor turned himself into police later Thursday in the wake of the incident.

According to multiple witnesses, McGregor ran into the arena's loading dock and began hurling objects at a bus, which was taking a group of UFC fighters to a nearby hotel.

In a video posted by TMZ, McGregor is shown lifting a dolly and throwing it into one of the bus' windows.

"They stormed the building, got down to the loading docks where the fighters were getting on buses and started to attack the buses with trash cans, dollies," White said. "... This is the most disgusting thing that has ever happened in the history of this company."

The incident caused several cuts to the face of UFC fighter Michael Chiesa, who had been scheduled to fight Anthony Pettis at UFC 223 on Saturday. Chiesa's coach, John Wood, told ESPN that Chiesa was hospitalized and treated for "lots of small cuts."

The UFC said Thursday night that Chiesa had been deemed unfit to fight by the New York State Athletic Commission and the UFC medical team and was removed from the bout.

Two other fights were also canceled because of the incident.

Flyweight Ray Borg experienced problems with his eye from particles of glass. He was deemed unfit for his scheduled fight with Brandon Moreno because of multiple corneal abrasions, according to the UFC.

Also removed from the card was the featherweight bout between Artem Lobov and Alex Caceres due to Lobov's involvement in the incident.

According to White, Lobov, a longtime teammate of McGregor, was part of the group that attacked the bus.

Earlier this week, Lobov was involved in a minor hotel scuffle with UFC lightweight Khabib Nurmagomedov, who is also scheduled to fight at UFC 223. It is unclear whether the incident led to McGregor's actions.

"Right now, absolutely not," White said, when asked if he still wants to be in business with McGregor. "Do you want to be in business with Conor McGregor right now? Do you want to chase this guy for interviews and buy his fights? I don't think anybody is going to want to right now.

"I don't know if he's on drugs or what his deal is, but to come and do this and act like this? You're talking about a guy who has a baby. He just had a kid."

McGregor (21-3) hasn't fought in UFC since November 2016, when he won the lightweight belt. He made the biggest payday of his career in a boxing match with Floyd Mayweather in August and has not fought since.

Prior to Thursday, White had said McGregor would "100 percent" return to UFC in 2018.