Minneapolis/St. Paul Int'l Airport - As tens of millions of people fly out of MSP every year, many are lawfully checking firearms much like the shooter in Florida did, according to investigators.

"I guarantee here at MSP International it's happening right now. It's beyond common," said Peter Johnson, a security expert.

Johnson owns Archway Defense in Chanhassen and is a former air marshal who specialized in terrorism prevention.

"It seems to be if all the indications are correct that this would be the first of this style of attack," he said,

He believes it is the first time an attacker checked his weapon while flying and then used it to kill people at the following airport when he landed.

"There's a good chance he was at our airport before he transited down to Fort Lauderdale," she said.

A chance confirmed by NBC News which reports the shooter flew from Alaska overnight landing in Minneapolis Friday morning and then taking a different flight to Fort Lauderdale.

"From what we know, he didn't grab his luggage at the time," he said of MSP.

The TSA allows for gun owners, as do other countries, to carry their weapons in their checked luggage, but they have to declare it, and it has to be unloaded in a pre-approved case.

While some may now question whether firearms should be allowed in checked luggage, Johnson doesn't anticipate any changes and believes that is the wrong place to focus.

"This doesn't change anything from the sense of checking firearms, lawfully checking firearms," he said. "Where this changes for me is individual preparedness."

He recently trained hundreds of security workers at O'Hare in Chicago on how to prevent this very scenario. He trains both GI Joes and Average Joes on how to spot danger before it happens.

"Believe it or not people who want to commit violence to others, they bleed indicators and with training we can teach people what to look for," he said.

Whether that would have helped in Florida is unclear.

Meanwhile, airports across the country may increase their security presence, something MSP officials say travelers will see over the weekend.