A Colorado Department of Corrections officer fired his gun during a weekend brawl at Denver motorcycle show that left one dead and seven others injured, an attorney said Sunday.

The corrections officer was a member of a motorcycle group made up mostly of off-duty law enforcement that, on Saturday, clashed with members of another club at the crowded Colorado Motorcycle Expo, a gathering of such groups from around the country.

The two biker groups on Sunday blamed each other for inciting the violence. Three of the wounded were hit by gunfire. Another person was stabbed and three others suffered injuries from a fistfight, police said.

The melee started when members of the Iron Order Motorcycle Club, made up of predominantly police and military, were jumped by members of the Mongols Motorcycle Club, said John C. Whitfield, an attorney representing Iron Order and a member himself.

But Las Vegas attorney Stephen Stubbs, who represents the Mongols, said it was Iron Order members who instigated the alcohol-fueled brawl by taunting them into an argument that led to the deadly shooting of a Mongols member.

"None of the Mongols involved in the altercation had a gun, not even one of them," Stubbs told The Associated Press. Another club member was among the injured, he said.

The corrections officer fired in self-defense, Whitfield said. He would not say whether he fired the fatal shot. Prisons spokeswoman Adrienne Jacobson confirmed an employee was involved in the shooting but would not identify him. He was not in police custody as of Sunday night, Whitfield said.

Whitfield said one Iron Order member was shot, another stabbed and a third beaten.

"We don't have any issue with the Mongols," he said.

Denver police have refused to release details about what happened or identify the clubs involved. Police spokeswoman Raquel Lopez said she wasn't aware of any arrests as of Sunday night, and detectives were trying to identify more than one shooter.

Denver Health Medical Center, where the injured were being treated, said three patients remained in critical condition and three in stable condition Sunday.

The violence put new focus on Iron Order, made up mostly of police officers and military personnel, and the Mongols, recognized by law enforcement as a highly-organized criminal gang. Members of the Mongols in Denver were charged with drug trafficking, firearms violations, witness tampering and other crimes during a nationwide racketeering investigation involving the group in 2008.

That investigation had nothing to do with the people at Saturday's show, said Stubbs, who disputed Whitfield's self-defense claim.

Iron Order had about 15 members in attendance, Whitfield said.

Stubbs said he believes Denver police are releasing few details because the Iron Order membership includes law enforcement officers.

Lopez said few details were being released because investigators were still trying to piece together what happened.

The Colorado Motorcycle Expo was being held at the National Western Complex and was scheduled to go through Sunday, but the city ordered organizers to cancel its Sunday events after the incident.

A statement posted on the event's website said it didn't have any information and apologized to vendors and patrons for any inconvenience.