MONROE -- A rivalry between two central Utah high schools went beyond jeers, cheers and touchdown passes: A dead sheep was hung from a goalpost the night before this week's big football game.

"This is not just a childish prank," said John Fox, chief investigator for the Humane Society of Utah. "An animal died because of this."

Sevier County sheriff's Deputy Russell Mason said: "Maybe it got a little out of hand."

The sheep was shot in the head, dragged onto the South Sevier High School field and fastened to the goalpost with a chain and padlocks.

Authorities were interviewing seven Richfield High School students who could face charges of theft, cruelty to animals, vandalism, trespassing and criminal mischief.

South Sevier coach Travis McAllister said the sheep slaying fired up his Rams. They defeated Richfield 26-6 Wednesday, with a fourth-place slot in the Division 2-A playoffs on the line.

"It's part of the rivalry," McAllister said. "It gives our kids an incentive to play harder."

He acknowledged chuckling after learning about the dead sheep, but said it went too far.

"Your retaliation needs to be on the football field," he told his players.

Mason said charges would not be filed until authorities completed interviews, perhaps Monday. Students also could be punished by school administrators.

"We do not condone that," Sevier School District Superintendent Brent Thorne said. "It is highly inappropriate."

This wasn't the first prank. Richfield fans once added an "A" to South Sevier's "SS" on a nearby mountain.

This story appeared in The Daily Herald on page A1.