Nurmagomedov made McGregor tap out in the fourth round of the fight, but he was apparently not ready to stop fighting. He climbed over the cage, jumped into the audience and began fighting various parties.
Meanwhile, members of Nurmagomedov's party went inside the octagon to begin an assault on McGregor. Video of the scene shows at least two members of Nurmagomedov's posse hitting the Irish fighter.
Three members of the Russian grappler's entourage were arrested later on due to their parts in the incident.
Security and onlookers eventually broke up the chaos, with both fighters being escorted out of the arena by police.
UFC President Dana White was apparently outraged over the brawl and refused to give Nurmagomedov his victory ceremony due to fear of audience interference.
According to The Blast, White said the Nevada State Athletic Commission would now investigate the fight, with UFC cooperating and giving them the footage from the event. Nurmagomedov could possibly be suspended for his actions, and the entourage members involved in the assault could be deported.
Both fighters have since spoken out about the fight and resulting chaos.
Good knock. Looking forward to the rematch.— Conor McGregor (@TheNotoriousMMA) October 7, 2018
McGregor simply wrote on Twitter, "Good knock. Looking forward to the rematch."
Nurmagomedov attended a post-fight press conference and deflected the heat he received back towards McGregor for his previous provocations and actions.
"He (McGregor) talk about my religion, he talk about my country, he talk about my father, he come to Brooklyn and he broke bus. He almost kill a couple of people," Nurmagomedov said. "Worry about this. Worry about this s—. Why people talk about I jump over the cage?"
He added, "This is respect sport. This is not trash talking sport. I want to change this game. I don't want people talk s— about opponents, talk s— about his father, religion. You cannot talk about religion, nation, you cannot talk about this stuff."
UFC has not offered an official statement on the matter as of press time.
Photo Credit: Getty Images / Harry How