Hundreds of officers tried to protect the Super Bowl parade. Here's why it wasn't enough.

The security presence at the Chiefs’ Super Bowl celebration in Kansas City, Missouri, on Wednesday was intense, but experts aren't surprised that hundreds of law enforcement officers weren't able to prevent the deadly shooting and chaos that unfolded.

There were over 800 officers stationed at the parade, along with officers with sniper rifles on building rooftops, which experts said is not unusual for a large event like a victory parade. It's all a part of a growing, uphill battle to secure events from the threat of gun violence in the United States.

On Friday, two juveniles were charged in connection with the shooting that left one person dead and 22 wounded.

Security experts say in a nation awash with firearms, large events always pose safety risks that even the most stringent security measures can't always catch before they happen. In a world where mass shootings have targeted churches, schools, grocery stores, concerts and now, a Super Bowl victory parade, those security measures are becoming more commonplace in everyday American life.

"There is a risk factor when you go to a concert or or a venue or an event. That is the world we live in," law enforcement and security expert Adam Bercovici, a retired Los Angeles Police Department lieutenant and former owner of a security company, told USA TODAY.

Complicating matters, Missouri has some of the laxest gun control measures in the country, according to gun control advocacy and research group Giffords Law Center to Prevent Gun Violence. Since 2017, it has been legal for people to carry concealed, loaded guns without a permit or background check, according to Giffords.

Screening for guns at big events is difficult

Experts told USA TODAY that there is only so much law enforcement and event security can do to prevent a shooting at an event like a parade or large music festival, even if security tries to keep guns out of the event.

It's especially difficult if not impossible to screen people for weapons when there aren’t clear entry and exit points. In that situation, officials have to rely on their intelligence in the crowd from a combination of uniformed and undercover officers.

"You can't metal detect all those people," Bercovici said. "So the next best option is to have real intelligence on the ground that can maybe see a firearm or weapon before it's used."

A combination of uniformed officers and officers undercover in plain clothes would have been trained to survey the crowd’s behavior and look for potential threats. For example, someone wearing a large coat in warm weather might stick out as trying to hide a weapon. But at a parade in February, it would be a lot easier to hide a large firearm under a big coat.

Officials said an estimated 1 million people were in downtown Kansas City for the parade. The city's population is roughly half of that, and the greater metropolitan area has about 2 million residents.

"Those are impossible numbers" of people to effectively manage, said Bercovici, who was part of law enforcement planning and response for Los Angeles Lakers events and victory parades as part of the LAPD. "Eight hundred police officers to deal with a million people ... do the math."

US event security keeps trying to keep up with threats

Over the last few decades, large event venues have been increasingly recognized as potential targets for terrorism, and more recently, for mass shooters.

That's led to years of increased safety screening measures and technology at event venues, said Steve Kaufer, a security expert and the president of Inter/Action Associates consulting group.

Twenty years ago, you might go through a metal detector to get into a large event, but nowadays, people can expect more thorough screening everywhere from a concert to a small venue like a nightclub. To go to a ball game at Nationals Park in Washington, D.C., spectators can only bring in bags the size of a wallet or clutch, or certain larger bags that are completely clear.

These security methods are “very effective,” Kaufer said. “But there are certainly workarounds for somebody that wants to get a weapon in place.”

In the future, Kaufer expects more and smaller venues to adopt screening technology and larger venues to have technology that allows for faster screening. A combination of metal detection and artificial intelligence to analyze items will make event screening much more efficient, he said. After all, forcing people to wait in too long of a line to get through security can spark the very kind of aggression security is trying to prevent.

What are the gun laws in Kansas City?

Kansas City, where largely Democratic leaders have been grappling with rising rates of gun violence, bans the firing of guns within city limits, but is bound by state laws that prohibit cities from enacting stricter measures than the state has. Kansas City Mayor Quinton Lucas and mayors across the country have called for new laws to address gun violence, including mandating universal background checks.

The state doesn't prohibit openly carrying guns, but in Kansas City it's only legal to do so with a state concealed carry permit.

While law enforcement officers at a parade might be on the look out for potential threats, spotting a firearm in a place where it's legal to have one might not on its own be a clear sign of brewing violence, Kaufer said. Still, it is a good idea for officers to check in with someone carrying a gun or at least keep an eye on them.

Even in a state that allows guns to be carried in public, "is it really appropriate that somebody brings a long gun, or any gun, to this kind of event?" Kaufer said. "If we can prevent those kinds of things from happening, is it a balance of, 'we're an open-carry state, but we're going to say that you can't open carry to an event where there's an assemblage of more than X number of people.'"

Contributing: Cybele Mayes-Osterman, USA TODAY; The Associated Press