Following the Sept. 11 terrorist attacks in 2001, Congress established the TSA. Within a year, the TSA assumed responsibility for security at the nation's airports and deployed a federal workforce to screen all commercial airline passengers and baggage.
The TSA says every day, about 50,000 officers screen 1.8 million passengers and their luggage at more than 450 airports across the country. They use imaging technology to screen passengers for any illegal items which may be hidden under their clothes or in their carry-on bags.
"These folks are the experts in screening of passengers. TSA as well as AFGE (American Federation of Government Employees) take great pride that since 9/11, there has not been a hijacking in this country; there have been no planes crashing into buildings. These folks are on the job every day, doing a great job protecting this country," said AFGE president David Cox.
Firearms are some of the most concerning prohibited items that TSA employees are on the lookout for. The TSA says as of September, officers have found more than 1,300 firearms this year at checkpoints across the nation.
It was more than a decade ago that gunfire last rang out at LAX. On July 4, 2002, Hesham Mohamed Hadayet, an Egyptian national, opened fire at the El Al ticket counter, killing two people. Hadayet was shot during the attack by an airline security guard.
On Friday, it was a TSA officer who lost his life -- the first to die in the line of duty, according to the union. Three other officers were also wounded, and like most TSA employees, they were not armed. The only TSA employees that can carry firearms are federal air marshals.
The TSA says more than 3,800 improvised explosive drills are conducted every day at airport checkpoints, and while workers received hundreds of hours of training, their union president says he doesn't believe there was any way to prepare for Friday's deadly incident.