The United Kingdom's second-biggest airport has been closed for over 12 hours after drones were seen over the airfield in what police described as a "deliberate act."
Police were on Thursday hunting for the drone operators who brought London's Gatwick Airport to a standstill, causing travel chaos for hundreds of thousands of passengers just days before Christmas.
Flights were diverted or grounded at Gatwick after two drones were spotted near the airfield at around 9 p.m. Wednesday night.
The airport was briefly opened again at 3 a.m. but closed 45 minutes later after more drones were reported, Gatwick said in a statement.
It is illegal to fly drones within 1 kilometer (0.6 miles) of a UK airfield boundary, and 20 police units from two forces were searching for the perpetrators in what has turned into a painstaking game of cat-and-mouse.
"Each time we believe we get close to the operator, the drone disappears; when we look to reopen the airfield, the drone reappears," Sussex Police Superintendent Justin Burtenshaw told the UK's Press Association.
There is no indication the incident is terror-related, Sussex Police said.
A spokesperson for Prime Minister Theresa May called the act "irresponsible and completely unacceptable."
Gatwick, a major international airport located south of London, remained closed on Thursday morning, with passengers stranded at the terminal or re-routed to other airports.
Around 110,000 passengers on 760 flights were scheduled to depart and land at Gatwick on Thursday morning, a spokesperson told CNN.
Passengers due to land at Gatwick were instead arriving in Manchester, Luton or Heathrow in the UK, or even as far afield as Paris and Amsterdam.
One passenger, Matt, said on Twitter he was waiting to board a coach at Manchester in the north of England -- two hours after he was supposed to arrive at Gatwick at the other end of the country.
At Berlin's Tegel Airport, heavily pregnant British woman Imogen Fletcher was left stranded for hours after her EasyJet flight to Gatwick was canceled.
The IT developer told CNN she had been on her way home for Christmas with her husband and daughter, but on Thursday morning she was left scrambling to find another flight.
Passenger John Belo told CNN he was stuck on a plane at Gatwick for four hours. Belo had been due to fly to Porto in Portugal at 8.45 p.m. on Wednesday night, in what should have been a two-and-a-half hour journey. But after hours of delays he finally arrived in the city at 2 a.m. the following morning.
Chaotic scenes at Gatwick
Passengers stranded at Gatwick in the early hours of Thursday described "total chaos" inside the terminal, with flights suspended and little information from staff.
Eddie Boyes, who was due to fly to Odessa in Ukraine, was stuck at the terminal with his wife and four-year-old son for nine hours.
He told CNN they had received "no information from the airport -- any information I have managed to get has been from social media.
"We have been given food vouchers totaling £30 ($38), offered a hotel room initially but very shortly afterwards this was retracted."
"People are sleeping on the floor in south terminal," he said, adding it was an "utter shambles."
Gatwick doesn't usually operate overnight, but morning is its busiest time, an airport spokesperson told CNN. The spokesperson warned passengers not to make their way to the airfield without checking on the status of their flight first.
"We 're sorry for the inconvenience today, but the safety of our passengers and staff is our no.1 priority," the airport said in a statement.
Drones flying too close to commercial flights pose a serious threat to larger aircraft, and can be sucked into engines or crash into the cockpit window, injuring or killing a pilot.
Aircraft incidents involving drones have risen in recent years, prompting the UK's Civil Aviation Authority in July to introduce strict rules for operators.
It is illegal to fly a drone higher than 400 feet (120 meters), or within 150 feet (50 meters) of people and properties.
Drone operators found to have endangered the safety of an aircraft could also face up to five years in prison.
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