A university police officer working with the state to curb underage drinking was shot to death by an Orlando police officer outside the Citrus Bowl Saturday as fans were arriving for a football game, authorities said.

Mario Jenkins, a canine officer working with agents of the Division of Alcoholic Beverages and Tobacco, was killed, said police Sgt. Troy Williamson of the University of Central Florida. Williamson said Jenkins was wearing street clothes. He did not discuss the circumstances of the shooting.

"You've got about 50 police officers and beverage agents who are in complete shock," Williamson said.

Witnesses told the Orlando Sentinel that the incident started when an undercover officer tried to break up a tailgate party. When he encountered resistance, they said, he fired three shots into the air. An Orlando police officer saw the man with the gun and shot him several times, the newspaper said.

Authorities believe a third person was involved, said Barbara Jones, spokeswoman for the Orlando Police Department. Jones did not say whether the person was injured.

The shooting occurred before a game between the University of Central Florida and Marshall University, which UCF won.

"It's pretty freaky. You don't think you would see this at a UCF game," said junior Nicole Jorgensen, 22.