NEW YORK (TNS) — He's gone from cage matches to an actual cage _ a jail cell.

Mixed martial arts bad boy Conor McGregor was arrested early Friday for attacking a bus full of fighters at Brooklyn's Barclays Center.

Much like the beginning of a title fight, the 29-year-old former UFC lightweight champ kept his head up as he was escorted from the 78th Precinct stationhouse in Park Slope to an awaiting unmarked police cruiser hours after his arrest to face charges in Brooklyn Criminal Court.

More than 20 officers cleared a path for the fighter outside and blocked traffic for two blocks as McGregor, wearing a fitted blue-collared shirt and light-wash jeans was walked in handcuffs to the cop car.

McGregor is facing three counts of assault and one count of criminal mischief for Thursday's wig-out at the Barclays Center.

The foul-mouthed fighter and his entourage were caught on video Thursday hurling chairs and dollies at a bus inside the parking garage at the arena, TMZ first reported.

The video shows the modern-day gladiator picking up a metal barricade before a group of people stop him.

He then runs around the loading dock hunting for something to throw at the departing bus as his entourage tries to calm him down.

McGregor ultimately grabbed a hand truck and threw it at the bus, breaking a glass window, cops said. A handful of people were hit by flying glass.

A member of McGregor's posse, friend and fellow Irishman Cian Cowley, 25, was also charged with assault and criminal mischief, cops said.

UFC fighters Khabib Nurmagomedov, Rose Namajunas, Al Iaquinta, Karolina Kowalkiewicz, Ray Borg and Michael Chiesa were at the Barclays Center for a promotional appearance for a series of bouts scheduled to take place at the arena Saturday.

The bouts include a fight between Holloway and Nurmagomedov _ who will be squaring off for McGregor's lightweight championship belt.

McGregor lost his UFC title due to inactivity. He last fought in November 2016, when he beat Eddie Alvarez.

The UFC canceled fights scheduled for Chiesa and Borg after the two fighters were cut up and bloodied in the brouhaha.

Artem Labov was also dropped from the slate because of an altercation with another fighter on Wednesday. Labov was with McGregor during Thursday's fracas.

"The organization deems today's disruption completely unacceptable and is currently working on the consequences that will follow," the UFC said in a statement Thursday.

McGregor's last fight was in August, when, he stepped into a boxing ring for the first time to take on the undefeated Floyd Mayweather Jr., and was knocked out in the 10th round.

The brawl at Barclays Center is not the first time McGregor has flung more than punches at fellow fighters outside the ring.

In August 2016, McGregor hurled water bottles and cans at opponent Nate Diaz during a press conference days before their fight.

The Nevada Athletic Commission fined McGregor $25,000 and ordered he serve 25 hours of community service for his involvement in the fight.

An MGM security guard also sued the fighter for $95,000 in damages after he was struck in the back by a can McGregor allegedly chucked.

Later Friday, McGregor was released on $50,000 bond and faces multiple charges.