An Alaska man has been charged with using his son's football helmet to knock a coach unconscious after a Friday night game at Highland High School.

Tumua Fagota Siaumau, 47, of Anchorage, was unhappy with his son's performance in Granger's 34-7 loss to Highland on Friday, according to charges filed Tuesday in 3rd District Court.

When an assistant coach approached Siaumau, the man swung his son's football helmet at the coach, knocking him unconscious and breaking his jaw, court documents state.

The coach, Darius McCormick, was taken to the hospital for surgery.

Siaumau has been charged with aggravated assault, a second-degree felony.