The crowd began throwing beer cans and bottles, many of which were full, at the buses, climbing on the buses, kicking them, denting them and ripping off the license plates. Witnesses said some in the crowd were chanting, "Flip the bus! Flip the bus!"

"We were afraid to get off the bus," said Mike Woodson, who came with his wife and kids and HereForBeer.com from Omaha.

When the first few officers arrived, they had to back out and call for backup, Phillips, of the Lincoln Police, said. The tailgaters were continuing to throw full beer cans and bottles, this time aimed at the officers. LPD sent about 30 officers to the center. Lancaster County sent eight deputies. The Nebraska State Patrol helicopter flew overhead, and multiple police dogs were present. They began making arrests and ordering people to leave.

"The crowd was pelting officers and the cruisers with beer bottles and cans," Phillips said. "It took a while."

A sergeant was still on the scene at 8 p.m. Saturday. Phillips said police officials would be discussing what further action to take.

"We will be talking to our legal adviser to come up with a plan for the future," she said. "We'll be looking at this and ways that we can try to ensure this doesn't occur again for the safety of everybody."