Los Angeles Airport shooting comes after recent threats by facility employees

The shooting Friday at Los Angeles International airport comes on the heels of two serious incidents involving employees at the airport in recent weeks.

Last week, a second worker charged with setting a series of dry-ice bombs at the airport pleaded not guilty. Miguel Angel Iniguez, of Inglewood, Calif., entered the plea Oct. 22 to one felony count of possession of a destructive device near an airplane.

The 41-year-old supervised workers at LAX for ground services company Servisair. Prosecutors allege that Iniguez and another airport employee, 28-year-old Dicarlo Bennett, made a total of three dry ice bombs near airport terminals on Oct. 13, but only two of them exploded. No one was injured.

Bennett pleaded not guilty earlier this month and is being held on $1 million bail. Iniguez is being held on $500,000.

In September, a security screener at the airport was taken into custody after quitting his job and making threats that led officials to clear and search terminals at the airport, according to the FBI.

Nna Alpha Onuoha, 29, was arrested and remained in custody on suspicion of making threats pending additional investigation.

A search of his otherwise empty apartment in suburban Inglewood turned up a note containing unspecified threats that cited the Sept. 11 anniversary. Additional details of the contents of the letter were not immediately provided.

No harmful materials were found at the airport or the man's apartment, the FBI said at the time.

The Los Angeles Police Department Bomb Squad also inspected a package allegedly left at TSA's headquarters in the airport after he resigned from his job, and the package was addressed to another agency employee, officials said.

The officers found no harmful contents in the package but turned up an eight-page letter in which Onuoha expressed disdain for the United States and referred to an event that led to a recent suspension from the job he had held since 2006, according to federal investigations.

Later, a man authorities believed to be Onuoha made two phone calls to TSA saying certain airport terminals should be evacuated. During one call, the man told an employee he would be monitoring to see if authorities would evacuate the terminals as instructed. No threats were found in authorities' search of the terminals.

No connection has been made between these incidents and the shooting Friday inside the airport's Terminal 3. The shooter, who has not yet been identified, opened fire with an assault rifle, according to authorities. Investigators believe the shooter acted alone.

Click here for ongoing coverage of the shooting at LAX

The Associated Press contributed to this report.