AMNA NAWAZ: Welcome to the "NewsHour."

Kansas City is coping tonight with the aftermath of the Super Bowl parade shooting that left one person dead and 22 others injured.

Half of them were under the age of 16.

GEOFF BENNETT: It was at least the 48th mass shooting in the U.S. already this year.

And it left local officials asking themselves about what more they could do to protect the public, when there was already a heavy police presence at the event.

It was a morning that began with revelry, nearly one million elated fans of the Kansas City Chiefs lining the streets on Wednesday, as players atop a double-decker motorcade wrote out the high of their historic Super Bowl win.

PATRICK MAHOMES, Kansas City Chiefs: Kansas City, let me hear you one time!

(CHEERING AND APPLAUSE) GEOFF BENNETT: The victory lap culminated outside Union Station, where massive crowds gathered for one last rally with their home team.

Just minutes after it ended, the area, still packed with people, the celebrations turned deadly.

Pops of gunfire sent the crowd into a panic.

Fans suddenly found themselves scrambling to find cover.

LISA MONEY, Eyewitness: Well, the only thing I really saw was, it had become chaotic.

And I hear: "Down, down, down, everybody down."

And at about the same time, I see the SWAT teams jumping over the fence, and I'm like OK, this might be real.

This is supposed to be a celebration for everybody, everybody, and those of the surrounding area.

Just devastating.

GEOFF BENNETT: The shooting claimed the life of 43-year-old Lisa Lopez-Galvan, a popular community radio deejay.

She co-hosted "Taste of Tejano," a weekly show that brings traditional Mexican music to the radio waves of Kansas City.

One of her children, Marc, was reportedly shot in the leg.

In total, 22 people were injured by gunshot wounds.

Investigations are still unfolding, but authorities have ruled out terrorism.

STACEY GRAVES, Kansas City, Missouri, Police Chief: There was no nexus to terrorism or homegrown violent extremism.

This appeared to be a dispute between several people that ended in gunfire.

GEOFF BENNETT: Police say they detained three people, two of the minors, and recovered several firearms from the scene.

MAN: We tackled him.

WOMAN: We tackled him.

GEOFF BENNETT: But not without the help of some brave Chiefs fans, like Paul Contreras.

Cell phone video caught the moment he and several others tackled and held down a man who was running from police.

PAUL CONTRERAS, Tackled Suspect: I didn't think about it.

It was just a reaction.

I didn't hesitate.

It was just do it.

And as I'm tackling him, I see his weapon either fall out of his hand or out of his sleeve, because he was wearing a long jacket or like a Carhartt.

So when I seen that hit the ground, I'm like, oh, we got to take this guy down.

GEOFF BENNETT: City officials say the shooting happened despite the presence of 800 members of law enforcement, turning lethal in seconds.

Today, Mayor Quinton Lucas said he has no plans to cancel any large-scale events, including an upcoming St. Patrick's Day Parade.

QUINTON LUCAS (D), Mayor of Kansas City, Missouri: I do think that there is a gun violence challenge in this community and many others.

And there certainly is a gun violence challenge as it relates to major events.

That, however, does not mean that Kansas City will stop having major events.

We will do all we can to make sure people are safe.

GEOFF BENNETT: For now, a community is still reeling from yet another high-profile event marred by gun violence.