Esteban Santiago grabbed his bag from the luggage carousel at the Fort Lauderdale-Hollywood International Airport and walked to the bathroom.

There, he pulled bullets and a 9 mm pistol from his baggage, loaded the weapon and returned to fire randomly at his fellow travelers, authorities said Friday.

A minute later, they said, he had killed five people, injured six and raised questions about how a person bent on harming people could legally fly across the country with a gun, then use it to attack unsuspecting passengers.

The answer: very easily. The Transportation Security Administration allows passengers to carry guns and ammunition in their checked luggage, provided they follow the rules.

The gun has to be locked in a hard-sided case. Usually, there’s a form to fill out. The gun can’t be loaded, but the rules allow passengers to also carry ammunition, sometimes in the same case. The TSA has a helpful video with cheery music detailing the process.

Santiago, an Army veteran from Alaska who complained that the government was controlling his mind, was arrested following the mass shooting and remained jailed Saturday in Broward County, Fla.

Under Florida law, people can’t carry guns in airport terminals unless they’re still in the case, although a bill before the legislature would allow people to openly carry guns in public places, including airports.

Passengers routinely check their weapons at the Ted Stevens International Airport in Anchorage, where Santiago initially departed from, Jesse Davis, the chief of police, told The Washington Post.

“We’re a big hunting state, so we get quite a lot of that,” he said, adding that for Santiago’s check-in procedure, “everything appeared normal.”

Passengers evacuate from Terminal 1 at Fort Lauderdale–Hollywood International Airport on Friday. (Paul E. Kostyu via Associated Press)

Rep. Debbie Wasserman Schultz (D-Fla.), whose district includes the airport where the mass shooting occurred, said she plans to revisit rules for flying with firearms when she returns to Washington this week.

“While we take a look at balancing the public’s need to be able to freely travel, at the same time we need to protect the traveling public who is traveling alongside someone who may decide to do them harm,” she said. “Federal rules do allow for firearms to be carried in checked baggage not in carry on baggage and there were procedures that were followed in this case.”

She said that she also plans to examine policies on unsecured areas in airports and other places frequented by the traveling public. “We need to take a hard look at the security around baggage claim areas.”

According to the TSA, guns are allowed in checked baggage, but lighters shaped like guns aren’t. Also prohibited in checked bags: many aerosol cans, electronic cigarettes, liquid bleach, recreational oxygen, safety matches and most spillable batteries.

While carrying guns in checked baggage in generally allowed, passengers who attempt to carry firearms into the seating areas of planes can face stiff penalties and prison time.

That doesn’t stop many people from attempting to tote guns onto airplanes anyway.

In 2015, TSA officers discovered a record 2,653 guns in carry-on bags at airport security checkpoints, a 20 percent jump from 2014.

Numbers for 2016 aren’t available yet, but in one week last year, officers discovered a record 78 guns in carry-on bags, according to the TSA’s blog. Sixty-eight were loaded.

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