Khabib Nurmagomedov of Russia holds down Conor McGregor of Ireland in their UFC lightweight championship bout during the UFC 229 event inside T-Mobile Arena in Las Vegas. Harry How/Getty Images

The UFC lightweight championship fight Saturday between audacious challenger Conor McGregor and undefeated champion Khabib Nurmagomedov at T-Mobile Arena in Las Vegas was by many accounts a well-contested bout, concluding with the Russian keeping the 155-pound title by submitting McGregor in the fourth round through a rear-naked choke.

But it was a brawl that immediately unfolded after the fight that has garnered the most attention.

Mere seconds after McGregor tapped out, Nurmagomedov appeared to direct comments to the Irish fighter and pointed at him. He then immediately climbed over the Octagon fence and attacked McGregor's jiu-jitsu coach Dillon Danis, a mixed-martial arts welterweight. Security could be seen restraining Nurmagomedov and Danis.

McGregor then attempted to jump over the Octagon fence after Nurmagomedov but was restrained. While on top of the fence, he appeared to exchange punches with a member of Nurmagomedov's team.

It didn't end there.

More members of Nurmagomedov's entourage jumped into the Octagon to attack McGregor before being restrained by security.

According to UFC president Dana White, three members of Nurmagomedov's team were arrested but later released because McGregor declined to press charges.

White said the Nevada State Athletic Commission had withheld Nurmagomedov’s $2 million purse pending an investigation and that fines and suspension can be expected. White described it as "a very bad night" for the league and said he was "so disappointed" by how the main event ended.

The fracas is likely retaliation for McGregor and his camp's infamous attack in April on a bus carrying Nurmagomedov at Barclays Center in Brooklyn.

In the post-fight press conference, Nurmagomedov was remorseful about the aftermath of the fight.

“First of all I want to say sorry to Nevada Athletic Commission and second to Vegas,” he said.

“I know this is not my best side. I’m a human being.”

But Nurmagomedov, who had said Russian President Vladimir Putin called him to say "congratulations," later placed blame on McGregor.

“I don’t understand how people can talk about how I jump on the cage,” Nurmagomedov said. “He talked about my religion, he talked about my country, he talked about my father.

“He came to Brooklyn and he broke a bus, he almost killed a couple of people. What about this s---? Why do people talk about me jumping over the cage? I don’t understand. This is a respectful sport, not a trash-talking sport. I want to change the game, you cannot talk about religion, about nationality.”