DENVER -- Kansas City Chiefs quarterback Patrick Mahomes was ruled out of Thursday night's game against the Denver Broncos after suffering a right knee injury in the second quarter.

The NFL's reigning MVP was injured on a quarterback sneak on fourth down with just over nine minutes remaining in the first half. As medical staff attended to him on the field, it appeared Mahomes' knee was straightened and popped back into place.

A cart came onto the field, apparently to take Mahomes for treatment. He was instead helped off the field by a couple of trainers. Players from both teams came by to offer encouragement.

Mahomes, 24, soon left for the locker room, walking under his own power but with a limp. He was in the X-ray room for only two minutes before the Chiefs ruled him out, according to the Fox broadcast. The team did not immediately offer details on the nature of the injury.

According to the broadcast, Chiefs coach Andy Reid said Mahomes was going to be OK because Mahomes told him so on his way off the field. The Chiefs' next game isn't until Oct. 27 against the Packers.

Mahomes entered Thursday's game hobbled by a left ankle injury he tweaked in a Week 5 loss to the Colts, when a teammate accidentally stepped on him. He played through the ankle injury in Sunday's loss to the Texans.

Veteran Matt Moore, who joined the Chiefs late in the preseason after backup Chad Henne broke his right ankle, replaced Mahomes.

Moore appeared in one game previously this season, throwing an incomplete pass against the Jaguars. Prior to that, he hadn't played in an NFL game since 2017 with the Miami Dolphins.