The slain security worker was the first TSA officer killed in the line of duty in the 12-year history of the agency, which was founded in the aftermath of 9/11.
The FBI and Los Angeles Airport Police identified the gunman as Paul Ciancia, 23, of Pennsville, N.J. He had apparently been living in Los Angeles.
A law enforcement official, speaking on condition of anonymity because the person was not authorized to discuss the investigation publicly, said Ciancia was wearing fatigues and carrying a bag containing a one-page handwritten note that said he wanted to kill TSA employees and "pigs."
The official said the rant 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. The note and the gunman's rifle each had an orange TSA inspection sticker on it.
Ciancia had at least five full 30-round magazines on him, said the official, who was briefed at LAX on the investigation. The official said Ciancia was shot in the mouth and leg by two airport police officers. Another official briefed on the incident at LAX who could not speak publicly said the gunman had been shot four times but was "stable" when he was transported to the hospital.