DENVER -- Kansas City Chiefs guard Laurent Duvernay-Tardif is a medical school graduate but didn't need any particular knowledge to immediately realize the severity of Patrick Mahomes' right knee injury.

"Everybody could have known something was wrong," Duvernay-Tardif said.

Mahomes dislocated his right kneecap in the second quarter of Thursday night's game against the Denver Broncos. It was quickly massaged back into place by members of the Chiefs' medical staff, but the quarterback left the game at that point and didn't return.

Tight end Travis Kelce said, "His knee didn't even look like a knee. It was all out of whack. I couldn't even describe it."

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The length of the absence for Mahomes, the NFL's reigning MVP, was unclear. Until he's back, the Chiefs will be quarterbacked by 35-year-old Matt Moore, who finished the team's 30-6 victory.

Mahomes was injured on a fourth-down quarterback sneak. Afterward, coach Andy Reid defended the playcall.

"Not too many people get hurt on a sneak," Reid said. "It's a freak thing and it happens."

In the moments after the play, Chiefs center Austin Reiter found himself in a bad position, with Mahomes lying on top of him.

"I think I was just yelling, 'Get off me,' but I didn't realize it was him. And everybody's telling me, I'm hearing from the refs, 'Just stay still, stay still.' And I'm just laying on my stomach face down. I just had to listen to the refs and not move. As soon as I realized it was his voice, I was like, all right, I'm not moving an inch."

A cart came onto the field to take away Mahomes.

"He refused to get into the cart," Reid said.

He was instead helped off the field by a couple of trainers. Players from both teams came by to offer encouragement.

Mahomes soon left for the locker room, at first helped by trainers and later walking under his own power but with a limp.

The Chiefs understood the severity of the injury right away. They declared Mahomes out for the rest of the game almost immediately.

"He was saying, 'It's out, it's out,'" Duvernay-Tardif said. "Nobody really understood what he meant at that time and then we saw it. ... That's when we started panicking. Not panicking but seeing that he was not all right."

Awesome team win! Love my brothers! Thank you for all the prayers! Everything looking good so far! #GodisGood #ChiefsKingdom — Patrick Mahomes II (@PatrickMahomes) October 18, 2019

Mahomes was in good spirits in the locker room and on Twitter after the game. TV cameras caught Mahomes leading a postgame cheer in the Chiefs' locker room while wearing a sleeve on his right leg.

Off camera, he gave a shoutout to his replacement, who might have to hold the Chiefs' Super Bowl hopes together until Mahomes can return.

"[He said,] 'How about my guy?'" Moore said. "Guys cheered."