Police in Los Angeles, California, have launched an extensive investigation into reports of an active shooter at the LAX Airport that prompted massive evacuation.
Security officials placed the international airport on a temporary lockdown on Sunday night, after receiving reports of an ongoing shooting at terminal 8.
Unconfirmed reports stated that people had barricaded themselves inside a café as a safety measure.
However, police and other security agencies found no evidence of a shooter.
“Report of shooting at Los Angeles International Airport proven to be loud noises; no shots fired but investigation continues to locate source,” LA police said in a tweet.
Upon receiving the initial reports, police had evacuated all passengers to the tarmac. But allowed them back into terminal for re-screening.
“Police searching LAX after reports. All precautions being taken to ensure safety of public. Remain calm. Thank you for your cooperation,” the airport police had first said in a tweet.
Social media footage pointed to mass evacuations and a heavy presence of security forces at the LAX. It was not immediately known if anyone was shot.
The Los Angeles Fire Department also responded to the scene and tweeted that “no significant incident” has been noted.
The situation also caused a massive traffic jam at and around the airport.
The apparent false alarm comes only two weeks after a similar one at John F. Kennedy International Airport in New York.
In that incident, people also called security forces after they thought a shooting was unfolding. Soon after that, various social media networks were flooded with footage of chaos at the airport.
Before things got really crazy - a man in a Zorro costume with a plastic sword was arrested. pic.twitter.com/COdNEIb1pL"No shots fired, no injuries, investigation continues to locate source," Mr Neiman wrote on Twitter.
A man wearing a black Zorro costume and wielding a plastic sword has been detained by Los Angeles police following reports of an active shooter and a mass evacuation at LA International Airport.
LAX Airport went into lockdown after police received false reports of an "active shooter" and ordered passengers onto the tarmac and out of terminals about 9pm local time.
"The 911 calls came from terminals 4, 7, and 8, law enforcement sources said," NBC News reported.
All terminals have since been cleared and passengers are proceeding through federal security screening in all terminals, LAX Airport said in a statement.
No shots were fired, according to the LA Police Department.
LA Police spokesman Andy Neiman said the reports of a shooter were spurred by loud noises only, and authorities were still investigating the source.
Before things got really crazy - a man in a Zorro costume with a plastic sword was arrested. pic.twitter.com/COdNEIb1pL"No shots fired, no injuries, investigation continues to locate source," Mr Neiman wrote on Twitter.
— sam macon (@sayczars) August 29, 2016
Earlier, passengers started tweeting about a security incident at the airport as posts flooded in on social media about reports of an active shooter. Videos showed passengers bolting from the airport terminal as someone yelled "get out ... run" before the sound of sirens could be heard and police cars arrived.
NBC nightly news anchor Lester Holt was caught up in the chaos.
"Arriving at LAX off flight when people started pouring out of term 4 onto Tarmac," Mr Holt wrote on Twitter.
"Security said 'shots fired. Run!'
"Now in vehicle on taxiway."
Mr Holt said witnesses told him she heard "pops" in terminal four at LAX.
"Others say they just heard 'run!'
"Those evacuated to Tarmac just allowed back in."
Police are on the scene and have urged people to remain calm.
"All precautions being taken to ensure safety of public," LA Airport PD wrote in a statement.
"Remain calm. Thank you for your co-operation."
A statement from LAX Airport later said an "individual in Zorro costume has been detained by LA Airport PD".
Active shooter at #LAX we're all evacuating holeee shitpic.twitter.com/hbadkjoV0R— Dennis (@sure_jan) August 29, 2016
The man in the Zorro costume was captured on film at the airport as he was surrounded by at least six police officers with their weapons drawn and a police dog, in the time leading up to the evacuation.
"Get on the ground," one of the officers repeatedly yelled.
The man rolled off a chair, face down on the ground onto his hat and cape, before the officers moved in and handcuffed him.
"Before things got really crazy - a man in a Zorro costume with a plastic sword was arrested," the Twitter user wrote.
"Cannot confirm that Zorro man caused the ensuing chaos, but it would be one helluva coincidence."
It is not yet known if the arrest was linked to the mass evacuation at LAX International Airport.
Flights have been delayed.
Hundreds evacuating onto runway currently at #LAXpic.twitter.com/SUKgMPtreB— Ross Greenberg (@Rossegreenberg) August 29, 2016