One person is dead and up to seven people injured after a gunman opened fire at Los Angeles International Airport.
One of the injured is a uniformed Transportation Security Administration employee who was manning a security checkpoint inside the airport's Terminal 3.
At least "three or four" other TSA employees were injured in the attack with seven people in total reported injured, six of which were taken to hospital.
It is understood the shooting occurred at 9.20am in Terminal 3 when a man pulled an assault rifle out of a bag and began to open fire in the terminal area.
According to police, he proceeded into the screening area and continued shooting. He then walked through the screening area and entered the "airside" of the airport.
Airport police then pursued the gunman through the termanal, engaged him in gunfire and "successfully took him into custody".
Police said he they believe he was a "lone shooter".
"We believe he was the only person armed in the incident," a spokesman said.
"There is a tremendous amount of investigative work that will need to be done."
A spokesman for Los Angeles Intertational Airport said LAX was accepting flights but at roughly half its usual capacity.
There has been media speculation that the gunman was employed by the TSA, and opened fire on his colleagues.
One eyewitness, speaking to a local television news crew, said the shooter was dressed in blue, and "looked like a TSA agent".
The eyewitness said he was armed with a "long gun" and a handgun. Police later said the shooter was armed with an assault weapon.
The shooter was screaming as he was shooting, but so far no witnesses who have spoken to media have been able to articulate what was being said.
A spokesman for the LAPD said the police would not speculate on the identity of the shooter until the investigation was properly underway.
Terminal 3 is one of nine terminals within the LAX complex. Since 2012, it has been the terminal base of the airlines JetBlue, Spirit, Virgin America and Virgin Australia.
Virgin Australia's daily flight, number VA1, landed at the airport minutes before it was closed to air traffic at 10am, local time.
The plane - with more than 350 Australians on board - was held on the tarmac for more than an hour while security personnel swept the terminal area.
VA1, which departed Sydney yesterday, is operated by a Boeing 777-300ER aircraft. It has a total capacity of 361 passengers when fully loaded.
One of the passegers, Alexander Reid, told Fairfax the mood on board was one of "calm, but there is a feeling of disbelief."
"The tarmac is full of planes but no movement. It's like a ghost town," he said.
Mr Reid said passengers became aware of the emergency as they began to switch on phones when the plane landed.
Another witness, Australian school student, Josh Odermatt, was evacuated from inside the terminal after it was placed on lockdown.
Mr Odermatt said police swept the airport room by room ahead of evacuating passengers and staff.
He said police told passengers to "step around" any bullet casings or blood, in order to protect potential evidence.
"The police are doing an incredible job, and grateful that we are all safe," Odermatt later posted on Twitter.
The Los Angeles Police department is describing the shooting as a "multi-patient incident."
According to media reports, the gunman has been apprehended. During the police search he was described as a male dressed in dark blue or black clothing.
Police have evacuated the terminal and several of the streets surrounding the airport.
Los Angeles mayor Eric Garcetti and the Chief of the Los Angeles Police Department, Charlie Beck, were both on the scene within the hour.
It is understood US president Barack Obama was also briefed on the incident.
All air traffic over the airport was been suspended and planes on the tarmac and taxiways at the airport were placed on "ground stop".
A ground stop prohibits aircraft from moving, landing or taking off. It is most commonly ordered during severe storms or security emergencies.
Sections of the airport are slowly re-opening.
Local television stations have broadcast footage of officers being deployed around LAX and into terminals 2 and 3, as well as at least one officer being treated by paramedics at the scene.