Chiefs Cancel Practice After Player Suffers Medical Emergency

10:02 AM PT -- The player who suffered the medical emergency was reportedly BJ Thompson -- a defensive end who Kansas City selected with a fifth-round pick in the 2023 NFL Draft.

Thompson, 25, played in just one game in his rookie season, logging two tackles.

A Kansas City Chiefs player suffered a medical emergency on Thursday morning ... and now, the team's revealed it's canceled its planned practice in the wake of the scare.

The player has not yet been identified publicly by the organization -- nor has KC given an update on his status ... but, according to NFL Network's Tom Pelissero, it was "a backup defensive lineman" who suffered a seizure in a special teams meeting.

Pelissero reported the athlete went into cardiac arrest ... but, thankfully, trainers raced to his aid, got him in an ambulance, and he's now currently in stable condition.

The Chiefs had been slated to work out Thursday afternoon as part of their voluntary organized team activities. They said in a statement that practice has been called off -- and planned media availabilities have now been moved to Friday.

As we previously reported, the Chiefs recently made a trip to the White House to celebrate their second-straight championship ... with Patrick Mahomes, Travis Kelce and more hanging out with President Joe Biden.

The Super Bowl champs will have a bit of a break following their Friday practice ... as they don't kick off their mandatory workouts until next week -- when minicamp begins on June 11.