The firearm used to kill five people and injure eight others at the Fort Lauderdale, Florida, airport on Friday was legally checked in his luggage, ABC News reported. The gunman, who reportedly flew into the airport from Alaska, simply picked up his baggage, loaded the gun in a bathroom, and opened fire in the adjacent baggage claim area.

Though Florida is one of eight states that prohibits passengers from carrying a gun in any part of an airport — including the terminal area before the security checkpoint — there are no laws against checking an unloaded firearm in baggage as long as you notify the airport and follow certain guidelines such as keeping the gun in a hard-sided case.

Some Twitter users were surprised to learn this detail about the shooting.

Others expressed dismay over the fact that the gunman was able to store ammunition in the gun case.

But according to the Transportation Security Administration (TSA), "[s]mall arms ammunition, including ammunition not exceeding .75 caliber for a rifle or pistol and shotgun shells of any gauge, may be carried in the same hard-sided case as the firearm."

TSA - tsa.gov

There has been an ongoing debate about airport gun policy, specifically concerning a passengers' right to carry firearms in the unsecured part of the terminal.

"There is no justification for permitting firearms at any airport," an Airports Council International spokesperson told USA Today in 2008. But on the other side of the debate are those pushing for fewer firearm restrictions at airports. This includes lawmakers in Florida who were set to vote next week on a bill that would've removed the ban on carrying firearms in the unsecured terminal, according to Mediate.

The suspected gunman, identified by law enforcement as 26-year-old Esteban Santiago, was placed in custody shortly after the shooting. Santiago was reportedly discharged from the Alaska National Guard for "unsatisfactory performance," BuzzFeed News reported. Before joining the National Guard, he served in Iraq as a member of the Army Reserves from 2010 to 2011. Officials say it's too early to say what the shooter's motives may have been at the time of the shooting.