Footage appears to show Kansas City Chiefs fans chasing and tackling an alleged mass shooter after shots were fired at a Super Bowl victory parade.

One person was killed and 21 injured — including 11 children — when a blast of gunfire sent the crowd scurrying for safety in Kansas City on Wednesday (local time).

Police Chief Stacey Graves said three people were detained “and under investigation for today’s incident” outside the city’s landmark Union Station.

Graves said investigators had no known motive for the gun violence.

Kansas media have identified local mum and DJ Lisa Lopez-Galvan as the victim who died in hospital during surgery for a gunshot wound to her abdomen.

The Kansas City Star writes that friends confirmed the mother of two had died.

“She was the most wonderful, beautiful person,” said Lisa Lopez, a friend for decades (no relation).

“She was a local DJ. She did everybody’s weddings. We all know her. She was so full of life.”

Lopez-Galvan worked as a disc jockey for community radio station KKFI and co-hosted the program ‘Taste of Tejano, featuring Hispanic music.

Graves said she was aware of reports that some fans may have participated in the pursuit and capture of at least one of the suspects, and investigators were reviewing video of the incident.

Around a million people turned out to celebrate with the NFL champion Chiefs in downtown Kansas City, Missouri, on Wednesday (local time).

Fifteen victims suffered life-threatening injuries, Fire Department Chief Ross Grundyson said at a news conference.

Some 800 law enforcement officers were at the rally and parade that preceded it, including agents of the FBI and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).

All of the Chiefs players, coaches and staff who attended the victory rally were accounted for and safe, the National Football League team said in a statement.

Fans flee after shots were fired at the packed parade. Photo: Getty

Hours after the bloodshed, authorities were still sorting out the precise number and details of casualties.

Children’s Mercy Kansas City treated a dozen patients from the rally, 11 of them juveniles, with nine victims suffering gunshot wounds, a hospital spokesperson said. Graves said during the news conference that no children were wounded.

At least five people injured in the shooting were taken to University Health hospital, according to a spokesperson there.

The barrage of gunshots, fired outside near a garage near the station, came at the end of the victory rally following a parade, according to police.

Video posted on social media showed pandemonium outside the station with dozens of uniformed police officers, weapons drawn, running into the building as scores of bystanders fled in the opposite direction.

Rapid-fire gunfire was audible in footage posted online by ABC News.

Union Station, a 109-year-old Beaux Arts building that once served as a major US rail hub for passenger and freight traffic, is home to a museum and visiting attractions today and a terminal for Amtrak passenger service.

Its website describes its vision to “be Kansas City’s iconic symbol of inclusion, inspiration, lifelong learning, and its centre for civic celebration.”

A statement from the NFL said: “We are deeply saddened by the senseless shooting that occurred in Kansas City today following the Chiefs’ celebration. Our thoughts are with the victims and everyone affected.”

Missouri Governor Mike Parson and his wife were in attendance when shots were fired near the train station, but were safe and secure following the incident, he said on X, thanking law enforcement for its response.

Kansas Governor Laura Kelly was also present at the rally when the shots were fired.

The Chiefs on Sunday defeated the San Francisco 49ers in overtime to win the Super Bowl, 25-22.