At least one person was killed after a shooting/stabbing melee Saturday afternoon during a motorcycle expo at the National Western complex that possibly involved two motorcycle gangs.

At a 6 p.m. news conference, Denver Police Chief Robert White said four people were shot and one person was stabbed. One person died and three are in critical condition. Three others received minor injuries.

White said the motorcycle clubs involved will not be named at this time. No arrests have been made, but one person of interest in connection with the incident is being questioned.

Police believe gunfire was exchanged and are also investigating whether other law enforcement officers from outside Denver were involved. Off duty officers were at the expo before the shooting.

There was no security screening at the event.

White said police “strongly suspect there’s more than one shooter.”

Shortly before the news conference, the city and county of Denver sent out a news release announcing the second day of the 38th Annual Colorado Motorcycle Expo would be canceled.

White said Saturday’s events were allowed to proceed because there was a heavy police presence and the event was close to its scheduled closing time.

“We allowed them to finish out their evening,” he said.

Denver Health tweeted shortly before 2 p.m. that nine people had been transported to area hospitals.

At a 3:30 p.m. news briefing, Denver Health announced 7 patients were brought in after the shooting. One died, three are critical and three are stable.

Bob Cook witnessed the shooting. His booth for Quarterchaps, a leather goods company was located across from where the shooting happened.

He heard two shots fired and saw people dive under tables. He didn’t hear any arguments before the shooting and doesn’t know what may have prompted it.

He said there were puddles of blood on the floor, but minutes later, the scene returned to normal. “Everyone is so desensitized,” he said as he pointed to dried blood on the floor that people were walking over.

Britney Shaw was working at a jewelry stand when she saw a group of about 50 men brawling on the stairs, which are now covered in blood and cordoned off.

Denver Health Medical Center put its campus on a temporary precautionary lockdown to ensure patient and visitor safety. There were no threats made to the hospital. One officer on duty there has a semi-automatic rifle slung over his shoulder.

ER doctor Kevin McVaney said the hospital was able to handle the emergency. “We are very prepared for this number of trauma patients.” All seven arrived via ambulance and no other injured parties are expected.

Raquel Lopez, Denver police spokeswoman, said the disturbance happened at 12:48 p.m. Multiple shots were fired and at least one person was stabbed.

One witness, who asked to remain anonymous out of fear of retaliation, said the feud was started by rival biker gangs.

Police filled the parking lot. People who left the show and crossed the police tape are not being allowed back into the building.

No new attendees are being allowed in, but people who are still in the building have not been asked to leave and continue to mill about and shop leisurely.

Some of the people who came out are angry they won’t be let back inside.

Mary Eckhart, who left the building, said some people attending the show don’t even know about the violence.

She said she attends the expo every year and is angry that some feuding people “can’t control their tempers for one day.”

The Kicker Arena Cross Show, which is scheduled for 6:30 p.m. in the National Western Event Center, will go on as planned.

On Saturday evening, the city and county of Denver sent out a news release saying the second day of the expo would be canceled due to safety concerns.

The city, in conjunction with the Western Stock Show Association, owns the National Western Complex, which had been contracted for the two-day expo.

A refund policy will be administered to ticketholders.

The Arena Cross event being held at the National Western Events Center will go on as scheduled with shows at 7:00 p.m. tonight and 2:00 p.m. Sunday. Arena Cross has no relation to the Expo.

Staff writer John Ingold and Katy Canada contributed to this report.