One person has died and 21 people were wounded in a shooting in Missouri at the end of the Kansas City Chiefs' Super Bowl victory parade.

Officials said they treated eight victims who were in immediately life-threatening condition, as well as seven others who had suffered injuries that could prove life-threatening.

An area hospital confirmed that nine children were among the wounded.

Police said they have arrested three suspects in connection to the shooting.

The shots were fired west of Union Station, the train station in downtown Kansas City, which was close to thousands of fans who had gathered for the victory parade on Wednesday.

The parade ended outside Union Station around 14:00 local time (20:00 GMT), and local reports said Kansas City Chiefs players were still on a stage when shots were first fired.

The gunfire caused the watching crowd, including the city's mayor and his family members, to run for cover.

More than 800 police officers were already on the scene to monitor the parade, officials said, including on top of buildings to ensure the safety of those who had come to watch the parade. The city's fire department was also present to provide medical attention if needed.

Kansas City Police Chief Stacey Graves said officers responded immediately after the gunshots broke out and detectives who were on the scene immediatley opened an investigation.

At a news conference on Wednesday, Chief Graves said a total of 22 people were struck by gunfire - one of them is dead - and three individuals have been arrested.

The surviving victims were transported to three local hospitals, with the life-threatening cases being taken to hospital within 10 minutes of the shooting, officials said.

Children's Mercy hospital, which cares for patients under the age of 17, said it was treating nine children with gunshot wounds.

Local hospitals said they were also treating people who were not shot but who had suffered other injuries in the sudden stampede that followed the shooting.

City officials did not release the names or ages of the victims. They also did not share any information about the suspects who were arrested, including what might have led to the shooting.

A law enforcement source told CBS News, the BBC's US partner, that the shooting appeared to be the result of an argument that turned violent. The source said it was not terrorism related.

Police said they are still investigating a motive and are appealing for eye witnesses or anyone with information to come forward.

The shooting broke out as the city was celebrating Sunday's second straight Super Bowl win by the Kansas City Chiefs.

Video shared on social media showed officers streaming into the busy train station after gunfire was heard and victims soon after being taken away in ambulances.

Kansas City's mayor Quinton Lucas said he was inside the Union Station when he and others heard the sound of gunfire and started running.

"We went out today like everyone in Kansas City looking to have a celebration," Mr Lucas said at Wednesday's news conference.

In a statement, the Kansas City Chiefs said all of its players, coaches and staff, as well as their families are safe and accounted for.

The team added that it is "truly saddened by the senseless act of violence that occurred".

Mr Lucas said he was "heartbroken" that the celebration ended with a deadly shooting.

"I'm incredibly upset and disappointed. I was there with my wife, I was there with my mother. I never would've thought that we, along with Chiefs players, along with fans, hundreds of thousands of people, would be forced to run for our safety today," he said.

"I don't want us to have to in our country — for every big event — think about the concern of being shot," he added.