LOS ANGELES (AFP) - The gunman who opened fire at Los Angeles airport, killing one security agent, carried a note saying he planned to kill "multiple" officers, the FBI said on Saturday.

The handwritten note, found in a bag taken into the airport, showed that he "made a conscious decision to kill multiple TSA employees," said Mr David Bowdich, the head of the FBI's LA office.

He revealed the details as prosecutors announced two charges against Paul Anthony Ciancia, accused of murdering a Transportation Security Administration (TSA) agent.

Ciancia, 23, faces a possible death penalty on charges of murdering a federal officer and committing violence at an international airport, said a prosecution official.

The FBI official revealed more details about the incident, including about the note found in a bag that Ciancia took with him into Terminal 3 at LA international (LAX) airport, carrying the assault rifle he used.

"In the note that was handwritten by the defendant, that was signed by the defendant, we found a statement where he made a conscious decision to kill multiple TSA employees," said Bowdich.

"He addressed them at one point in the letter, and stated that he wanted to 'instill fear into their traitorous minds.'"

The officer who died, named as Gerardo Hernandez, 39, was the first TSA agent to die in the line of fire since the agency was created after the Sept 11, 2001 attacks.