The clash began after a beer garden became too crowded and people spilled on to Main Street.

"We're just trying to clear the crowd," said Scott Folsom, assistant Salt Lake City Police chief. He said he knew of no injuries and little property damage.

He described the ammunition as "stinger balls".

He says 75 to 100 officers were brought in to quell the disturbance and close off intersections. Some people in the crowds threw beer cans and bottles.