Story highlights Motorcycle clubs "possibly" involved in shooting, police Chief Robert White says

Colorado Motorcycle Expo canceled for Sunday, city says

(CNN) Shooting and a stabbing broke out at a motorcycle show in Denver on Saturday afternoon, leaving one person dead and seven people injured, authorities said.

Two rival motorcycle clubs were "possibly" involved in the violence at the Colorado Motorcycle Expo, police Chief Robert White said at a press conference.

The Denver Post quoted a witness , who didn't want to be identified because of fear of retaliation, as saying the violence involved rival biker gangs. Video taken after the shooting showed police talking to groups of men wearing jackets with motorcycle club patches.

White said about 10,000 people were inside the National Western Complex hall at 12:45 p.m. (2:45 p.m. ET) when shots were fired.

Investigators think two or more people exchanged gunfire, he said, but the cause of the shooting is still being investigated.

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