Keith Reaser injured and carted off the field during Monday practice

Kansas City Chiefs cornerback Keith Reaser suffered what appeared to be a serious injury during Monday morning’s practice session at Missouri Western State University in St. Joseph.

Initial reports said the injury occurred during the 11-on-11 drills, and Reaser was away from the play when it happened.

Reaser was unable to put weight on the leg and ultimately left the field on a cart.

And then the really bad news: after practice, Chiefs head coach Andy Reid said it appeared Reaser had torn an Achilles tendon — which is typically a season-ending injury.

This is a big blow.

Reaser was probably sitting in the fourth position on the cornerback depth chart behind Kendall Fuller, Bashaud Breeland and Charvarius Ward — and even though the Chiefs have 12 cornerbacks in camp to fill what will probably be about six spots on the final active roster, it is considered by most as a group with little depth.

Reaser has been down this road with the Chiefs before.

Placed on the Chiefs practice squad in the early part of the 2017 season after being released by the San Francisco 49ers, Reaser managed to get on the active roster for two games: the meaningless Week 17 game against the Denver Broncos and the playoff loss to the Tennessee Titans.

If things has played out differently in the second game, Reaser might have been one of the heroes of a playoff victory. He recovered Adoree’ Jackson’s muffed punt in the third quarter, which gave the Chiefs the ball at the Titans 28-yard line. The drive went nowhere, and the Chiefs had to settle for a 48-yard field goal attempt that Harrison Butker missed — a kick that if successful, might have put the Chiefs in a position to win the game.

A year ago, Reaser suffered a quad injury in training camp that forced the Chiefs to cut him with an injury settlement. He went on to have a big season in the now-defunct Association of American Football and was one of the first players signed by an NFL team when the league folded.

“It was unfortunate he had that quad injury last year,” Chiefs general manager Brett Veach said of Reaser when he was signed this past February. “I think he was a guy that was probably going to make our 90-man roster. He was a guy that we liked coming out of Florida Atlantic and he got hurt, didn’t go to the combine, and those guys are a little bit tricky in the draft because you don’t know if they’re going to get drafted at all or how late they’ll fall and putting a value on those guys is sometimes difficult.”

It worked out that despite those problems, Reaser got two chances to play for the Chiefs. If his injury is as severe at the Chiefs think, he might not get a third.