About 100 people were taken into custody and bridges over the Colorado River were shut to traffic, radio station KGMN-FM in Kingman, Ariz., reported.

The shooting occurred on the first floor of Harrah’s during the 20th annual River Run, a large gathering of motorcycle clubs that brought up to 80,000 people into the gambling resort this weekend, according to Larry Tunforss, a spokesman for the Bullhead City, Ariz., Fire Department.

Harrah’s director of marketing, Laura De La Cruz, said an altercation between rival motorcycle gang members erupted shortly after 2 a.m. She would not give any other details, referring questions to police.

Tunforss described the city as being in total lockdown. “Nobody can drive in or out of the city,” he said.

He said about 100 people inside the casino were either handcuffed or spread-eagled on the floor by police after the shooting.

Police dispatchers would only confirm a motorcycle gang was involved.

At Western Arizona Regional Medical Center in nearby Bullhead City, Ariz., nine men patients, some with gunshot wounds, some with knife stab wounds, were being treated, said hospital spokeswoman Ruth Padilla.

The hospital began receiving patients about 2:25 a.m., she said. Three men in critical condition with gunshot wounds were flown to University Medical Center in Las Vegas, she said.

Laughlin is located 80 miles southeast of Las Vegas, near the Arizona border.