"What happened is really every security planner's worst nightmare: the unsecured areas at LAX. It's really difficult to get a hold on what you're going to do about it," said security expert Jeffrey Simon.
LAX police and the TSA say they're now reviewing safety protocols after TSA agent Gerardo Hernandez was killed and several other people were wounded in Friday's shooting.
According to investigators, the alleged gunman, Paul Ciancia, carried an assault-style rifle through the lobby of Terminal 3 before opening fire.
On Monday, David Cox with the union that represents TSA officers issued a statement saying, "The sad truth is that our TSA officers are subject to daily verbal assaults and far too frequent physical attacks while performing their security duties. At this time, we feel a larger and more consistent armed presence in screening areas would be a positive step in improving security for both TSOs and the flying public."
LAPD Chief Charlie Beck says there are 160,000 people going through LAX every day, and that you can't control every one of them.
"Chief [Patrick] Gannon and I could make that airport 100 percent safe, but it would take you a day and a half to make your flight. That's the reality we have to live with in a country that's going to enjoy the kind of freedoms that we all want. I don't want to have to search every person and every car that goes into that airport. That would absolutely tie up the huge hub of commerce," said Beck.
LAX Police Chief Patrick Gannon said the gunman appeared to be a normal traveler as he entered the terminal and probably wouldn't have raised the suspicion of a police officer.
"One of the problems is how do you protect against terrorism without creating a fortress America," said Simon, who recently wrote a book titled, "Lone Wolf Terrorism."
Simon said this is a case of lone wolf terrorism and that there's no fail-safe way to stop all attacks at airports.
"Lone wolf terrorists are not going to be deterred by possible death sentences if they're caught. They're not going to be deterred if they can't penetrate security, because they'll just find another target. If they're determined to want to act, they're going to find an opportunity," said Simon.