At least one person has been killed and nine others injured after violence reportedly broke out between rival biker gangs.

Police in Denver, Colorado, confirmed that one person was dead and that a number of other people had suffered gunshot and stab wounds.

Officers said the incident happened at the Denver Coliseum, which was hosting the Colorado Motorcycle, described as the “largest motorcycle show & swap in the Rocky Mountain Region with antiques, custom motorcycles and more”.

The injured were taken to the to Denver Heath Medical Centre where multiple police officers were standing on patrol outside the emergency room entrance.

The Denver Post reported that one witness, who asked to remain anonymous out of fear of retaliation, said violence broke out after a feud started between rival biker gangs.

The injured were taken to the to Denver Heath Medical Centre where multiple police officers were standing on patrol outside the emergency room entrance.

Police filled the parking lot and people who left the show and crossed the police tape were not allowed back into the building, the paper said. It said the exhibition was permitted to remain open and people were not asked to leave.