PULLMAN, Wash. >>  Washington State quarterback Connor Halliday, the nation’s passing leader, was knocked out of Saturday’s game against Southern California with what appeared to be a serious injury.

It appeared that two players crashed into Halliday after he threw a pass late in the first quarter. The senior writhed on the ground, was strapped onto a stretcher, and driven off the field in a cart.

Washington State officials did not immediately disclose the extent of Halliday’s injury.

Halliday was replaced by freshman Luke Falk.

Coming into the game, Halliday led the nation with 3,833 passing yards. He had 32 touchdown passes and 10 interceptions. Halliday had thrown for 40 yards and an interception against Southern California when he was injured.