Hays ? A mysterious illness has sent four Fort Hays State football players to the hospital and sickened 21 other players and two coaches.

The four players were in fair condition at Hays Medical Center on Thursday. Dr. Randy Cook said they were being treated for an unusual form of pneumonia. The cause was not yet known.

“I think that the conclusion is obvious: that there is something in the football complex or facilities that is affecting the players,” school president Edward Hammond said. “We don’t know exactly what’s causing it, what the source is.”

The Tigers canceled Tuesday night’s scrimmage and Wednesday’s practice sessions because of the outbreak, but they resumed workouts Thursday morning.