What is a mass shooting? That depends on who you ask

CHICAGO (WLS) -- There are differing definitions of a crime that is committed hundreds of times a year across the country.

Dozens of mass shootings have happened in Chicago neighborhoods in recent years, and hundreds in America every year. But there are still misunderstandings about what constitutes a mass shooting and why.

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Depending on who is defining the crime, the rapid-fire attack in Willowbrook Township last summer might be a mass shooting, or it might not, even though 23 people were shot and one of them killed.

It was the same story in Michigan on Saturday. Thirty-six shots were fired and nine people were wounded, including an 8-year-old boy.

Lots of shots were fired at a mass of people, but because no one died, and many law enforcement agencies wouldn't categorize either as mass shootings.

Policies cause the confusion. A U.S. statute written in 2012 states that mass killings means three or more killings in a single incident. An FBI spokesperson tells the I-Team, "For the purposes of tracking crime data, the FBI defines a mass shooting as any incident in which at least four people are killed with a gun." The widely-cited Gun Violence Archive defines it as "four victims shot or killed, not including shooter."

"When you shoot someone, your intent is to murder them. More than two, simply in my view, would be a mass shooting," former longtime Orland Park Police Chief Tim McCarthy told the I-Team.

He now co-owns and operates a private security firm and famously survived what has been described as a mass shooting when he was a Secret Service agent protecting President Ronald Reagan in 1981.

"I think we've got to go back and change our thinking a little bit. And while we say a felon with a firearm is a Class Four felony, we need to treat it like a Class Four felony," said McCarthy.

The presidential attacker used a 22-caliber, six-shot revolver, proving that mass attacks don't require high-capacity guns.

"Six rounds out of a revolver was just about as deadly. To hit four people in 1.4 seconds. What we see now are mostly semi-autos. Revolvers can be just as deadly," said McCarthy.

He tells the I-Team that despite his 50 years in law enforcement, he doesn't have a good answer for how to roll back the crime tide that comes with high capacity weapons. But McCarthy does make the point that there are solid laws on the books that could be better enforced, including prosecuting and locking up more convicted felons caught with guns.