Kansas City (AFP) - The shooting at the Kansas City Chiefs' Super Bowl victory rally that left one person dead and 22 injured, including several children, was a personal altercation and two juveniles were among those detained, police said Thursday. 

Up to a million jubilant fans had gathered in unseasonably warm weather for the parade of NFL champions when shots rang out just before 2:00 pm Wednesday.

"There was no nexus to terrorism or homegrown violent extremism. This appeared to be a dispute between several people that ended in gunfire," Kansas City Police Chief Stacey Graves told reporters.

"We have subjects detained, two of which are juveniles. We are working to determine the involvement of others," she said, adding that several firearms were recovered. 

One person, 43-year-old Elizabeth Galvan, was killed, police said. Local radio station KKFI identified DJ Lisa Lopez-Galvan as the person who died, adding that her son and two other relatives were shot.

Stephanie Meyer, senior vice president at the local Children's Mercy hospital, said only three of the 11 children treated there still remained hospitalized Thursday and they "will recover" from their injuries.

Overall, the hospital treated 12 victims, nine with gunshot wounds and the rest with "incidental injury."

Two parade-goers, who gave their names only as Gracie and McKenna, said they heard a shouted warning to duck. 

"We heard a couple shots," McKenna told AFP. "Everyone just immediately, instinctively crouched down."

According to police, at least half of the gunshot victims were under age 16.

Graves thanked those in the crowd who "physically stopped a person who was believed to be involved in the incident."

Paul Contreras, who was with his three daughters, said he tackled and disarmed one of the suspected shooters before the police arrived.

"When I hit him from behind, I either jarred the gun out of his hand or out of his sleeve," Contreras said on CNN.

Victims were treated lying on the ground before being carried away on stretchers amid the crowds, while hundreds of police rushed to clear the area.

Just moments before the shooting, the championship players had been soaking up cheers at the end of the two-mile (three-kilometer) procession of double-decker buses.

Chiefs star Travis Kelce later said he was "heartbroken."

"My heart is with all who came out to celebrate with us and have been affected. KC, you mean the world to me," he wrote on X, formerly Twitter.

"Praying for Kansas City," quarterback Patrick Mahomes wrote on social media, while a statement from the team said they were "truly saddened by the senseless act of violence."

Kansas City, in the Midwestern state of Missouri, saw a record number of 184 homicides in 2023, according to local media. 

"I don't think in any way that this is Kansas City," Mayor Quinton Lucas told reporters Thursday, referring to the shooting. "I do think there is a gun violence challenge in this community and many others."

'Shame us into acting'

US President Joe Biden deplored the shooting and issued a rallying call for Americans to back his pleas for Congress to enact gun reform.

"Today's events should move us, shock us, shame us into acting," Biden said in a White House statement Wednesday.

Meyer, the hospital executive, said the shooting will scar the community not just physically, but also mentally.

"I think it's important that we talk about the tragedies and the lasting impact they're going to have on the mental health of not only the community but all of our kids," she told reporters.

Mass shootings are common in the United States, where there are more guns than people and about a third of adults own a firearm. 

The Chiefs were celebrating their third Super Bowl title in five seasons after beating the San Francisco 49ers in Las Vegas on Sunday.