BOULDER, Colo. -- Police used tear gas and pepper spray to disperse fans celebrating Colorado's victory in the Big 12 championship game.

Two officers were injured slightly, and 18 people were arrested Saturday night after the 39-37 win over Texas, police spokeswoman Jennifer Bray said.

Two people sought treatment for tear gas inhalation, while another was injured while running from the gas.

Police said they videotaped the crowd and will scan the tapes for suspects.

Some in the crowd of 500 lighted bonfires, tore street signs and traffic lights and tried to overturn cars. Another crowd of about 100 gathered a few blocks away.

Police used tear gas on the larger crowd and stinger grenades and pepper balls on the smaller crowd. Stinger grenades make a loud bang and bright flash and dispense small rubber pellets. Pepper balls are fired from a paintball gun.

The University Hill neighborhood has been the site of riots at least six times since 1997.

"It's disappointing that some people have still not learned how to celebrate responsibly," Police Chief Mark Beckner said. "What should have been a fun time turned into a malicious mob."