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 official was not authorized to speak publicly on the case and requested anonymity.

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 arrived at the airport in a black Hyundai and was not a ticketed passenger.

Ciancia is facing charges of murder of a federal officer and committing violence at an international airport. The charges could qualify him for the death penalty. It was not immediately clear when he would make a first court appearance given his medical condition.

In court documents and interviews, authorities spelled out a chilling chain of events, saying Ciancia walked into the airport’s Terminal 3, pulled the assault rifle from his duffel bag and fired repeatedly at 39-year-old TSA officer Gerardo I. Hernandez. He went up an escalator, turned back to see Hernandez move and returned to shoot him again, according to surveillance video reviewed by investigators.

He then fired on two other uniformed TSA employees and an airline passenger, who all were wounded, as he moved methodically through the security checkpoint to the passenger gate area before airport police shot him as panicked travelers hid in stores and restaurants.

It wasn’t clear why Ciancia targeted TSA officers, but what he left behind indicated he was willing to kill any of them that crossed his path, authorities revealed.

The letter in his duffel bag refers to how Ciancia believed his constitutional rights were being violated by TSA searches and that he’s a “pissed-off patriot” upset at former Department of Homeland Security Secretary Janet Napolitano.

“Black, white, yellow, brown, I don’t discriminate,” the note read, according to a paraphrase by a law enforcement official briefed on the investigation. The official spoke on the condition of anonymity because he was not authorized to speak publicly.

The screed also mentioned “fiat currency” and “NWO,” possible references to the New World Order, a conspiracy theory that foresees a totalitarian one-world government.

The letter also talked about “how easy it is to get a gun into the airport,” the law enforcement official said.

When searched, the suspect had five 30-round magazines, and his bag contained hundreds more rounds in boxes.

U.S. Rep. Michael McCaul, R-Texas, chairman of the House Homeland Security Committee, said on CNN’s State of the Union on Sunday that Ciancia’s actions show how difficult it is to protect travelers at a massive airport such as LAX.

The terminals are open and easily accessible to thousands of people who arrive at large sliding glass doors via a broad ring road that fronts the facility and is designed to move people along quickly.

“It’s like a shopping mall outside the perimeter, it’s almost like an open shopping mall,” McCaul said.

TSA Administrator John Pistole said the agency will need to work with each airport’s police agency “to see how we’ll go about in providing the best possible security.”

The shooting temporarily halted traffic at the nation’s third-busiest airport, stranding thousands of passengers and causing dozens of flights to be diverted to other airports. More than 1,500 flights and 167,000 passengers were affected nationwide, according to the Los Angeles Times.

On Sunday, flights at the airport were back on schedule and regular operations had resumed, LAX spokesman Marshall Lowe told the newspaper.

The FBI has served a search warrant on a Sun Valley residence where Ciancia lived, Ari Dekofsky, a spokeswoman for the FBI’s Los Angeles field office, said Sunday. Agents are still interviewing people, she said.

Authorities believe the rifle used in the shooting was purchased in Los Angeles. Ciancia also had two additional handguns that he purchased in Los Angeles, but which weren’t at the crime scene, a law enforcement official said. The official, who has been briefed on the investigation, was not authorized to speak publicly and requested anonymity.

The purchases themselves appeared legal, although authorities were still tracing them, and it’s unclear if the shooter used his own identification or someone else’s, the official said.

“He didn’t buy them on the street. He didn’t buy them on the Internet,” the official said. “He bought them from a licensed gun dealer — the rifle and the two handguns.”

Hernandez, a three-year veteran of the TSA, moved to the U.S. from El Salvador at age 15, married his sweetheart, Ana, on Valentine’s Day in 1998 and had two children.

The TSA said the other two officers wounded in the attack — James Speer, 54, and Tony Grigsby, 36 — were released from the hospital.

Brian Ludmer, a Calabasas High School teacher, remained in fair condition at Ronald Regan UCLA Medical Center and will need surgery for a gunshot wound to the leg. Two other people suffered injuries trying to evade the gunman, but weren’t shot.

The FBI was still looking into Ciancia’s past, but investigators said they had not found evidence of previous crimes or any run-ins with the TSA. They said he had never applied for a job with the agency.

(AP)