LOS ANGELES — The man who opened fire at Los Angeles International Airport, shooting employees and terrorizing travelers, accomplished two of his goals: kill a Transportation Security Administration officer and show how easy it is to get a gun into an airport.

Paul Ciancia’s deadly rampage left investigators to piece together what motivated his hatred toward the agency formed to make air travel safer after the Sept. 11 terrorist attack, but could ultimately lead to changes in the way airports are patrolled.

Ciancia was shot four times by airport police, including in the mouth, and remains heavily sedated and under 24-hour armed guard at the hospital, a law enforcement official told The Associated Press on Sunday.

The FBI said he had a handwritten letter, stating that he made the conscious decision to try to kill multiple TSA officers and “instill fear in your traitorous minds.”

The unemployed motorcycle mechanic who recently moved to Los Angeles from the small, blue-collar town of Pennsville, N.J., had a friend drop him at LAX on Friday just moments before he pulled a .223-caliber assault rifle from his duffel bag and opened fire, killing one TSA officer and wounding three other people, including two more TSA workers.

Officials do not believe that the friend knew of the shooter’s plans. Ciancia was not a ticketed passenger.