Kansas City Chiefs head coach Andy Reid revealed to the media that linebacker Derrick Johnson suffered a ruptured Achilles during Thursday's game against the Oakland Raiders, according to multiple reports.

The injury occurred in the first half of the game on a non-contact play. Johnson fell to the turf, grabbed at the Achilles on his left leg, and threw his helmet to the ground.

The injury is certain to end Johnson's season. It's disappointing news for the 12-year veteran as he missed all but one game in 2014 when he tore the Achilles in his right leg. He returned to play in every game of the 2015 season and had played and started in all 12 games this year. His absence will leave a gaping hole in the Chiefs' defense.

Inside linebackers Ramik Wilson and D.J. Alexander will climb the depth chart as a result.

The Chiefs won Thursday's game 21-13 to move to 10-3 and the top of the AFC West. If Kansas City is to reach the playoffs, they'll have to make it through the postseason without the four-time Pro Bowler.