A UFC news conference at the MGM Grand Hotel in Las Vegas turned violent on Monday after light heavyweight champion Jon “Bones” Jones and challenger Daniel Cormier engaged in a physical altercation on the event’s stage.

Jones and Cormier met face-to-face at the press event, which was meant to promote their upcoming Sept. 27 title match at the UFC 178 pay-per-view event, ESPN reports. Normally, challengers engage in a “stare down” at such events to hype up their upcoming match.

However, Jones and Cormier appeared to bump heads, prompting Cormier to shove the titleholder. An incensed Jones dropped his UFC light heavyweight championship and lunged at Cormier. UFC director of communications, Dave Sholler, attempted to prevent a brawl, but Jones pushed him out of the way.

Before long, the altercation had knocked over the stage’s canvas backdrop as Jones and Cormier continued to exchange blows. Eventually, security guards managed to separate the two fighters.

After the confrontation, Jones and Cormier each took to Twitter to continue their disagreement. At one point, Jones told Cormier that he “put [him] on [his] back in six seconds.”

Kirk Hendrick, the UFC’s chief legal officer, condemned their pre-fight battle. "This is certainly not a proud moment for the UFC organization," Hendrick said in a statement. "We expect more from our athletes, especially these two gentlemen, who are very well-trained and highly educated professionals. Their actions were clearly a violation of the UFC's code of conduct.”

“There are going to be ramifications. Whether you’re the champion, or this is your first fight in the UFC, there are going to be ramifications from the UFC for these actions,” he added.

Still, not everyone is convinced that the confrontation was entirely legitimate, especially given the event’s purpose -- to provide maximum exposure for the fight card ahead of UFC 178. Some outlets, including Deadspin, suggested that the altercation may have been staged.

Jones was originally slated to fight Alexander Gustafsson on Sept. 27, but Gustafsson was forced to withdraw from the match because of a knee injury. Cormier, who dropped from the heavyweight division to the light heavyweight division in February, was named as his replacement.

Jones has held the UFC light heavyweight championship since March 2011. UFC 178 will mark his eighth defense of the title.