Gatwick Airport remains closed due to a drone flying close to the airport, with cancelled flights stranding tens of thousands of passengers days before Christmas.
The disruption began at around 9pm on Wednesday when the airport reported that flights had been suspended and there were "reports of two drones flying in and around the airfield".
It said late Thursday it could not be reopened following further appearances of the devices.
"Gatwick's runway remains unavailable because of continued drone sightings," it said in an 11:00pm update.
Police and airport authorities believe they were being flown in deliberate act to disrupt the airport.
The unusually large drones had been spotted near the airfield more than 50 times over the 24-hour period, police said on Thursday night.
Detective Chief Superintendent Jason Tingley said officers believe the device is "larger than a domestic drone."
"Our working assumption is it's larger than what someone might buy online, we think it may have been adapted and developed."
He said firearms officers were now considering shooting the device down, despite authorities earlier saying that would be dangerous due to the danger of stray bullets.
"We have to take into consideration other people that may be in range and the impact of firing at a drone," Detective Tingley added.
Gatwick's chief operating officer Chris Woodroffe said it is a "terrible situation" for the 120,000 people who have had their travel plans disrupted.
"The issue from my perspective is that this is a criminal act, purposefully undertaken in order to cause this disruption, and I very much hope we bring the perpetrator to justice."
One woman, Julie Garghan, who is travelling with her sister Sarah, her sister's children and their elderly parents, expressed her frustration at the situation.
She told Sky News: "We should be on a beach now, the kids should be happy, dancing and looking forward to Christmas.
"The elderly travellers we have got with us should be more relaxed and not confined to wheelchairs.
"It is just so frustrating. Everything isn't as it should be. You can't plan for this – nobody planned for this."
Explaining the family's sleeping arrangements, she said: "We've had to set up under the stairs in the Departures area because there are no chairs; there are so many people here there are no chairs to lay the children on.
"We've had to fashion beds with what we had in our hand luggage. We've put towels down, trying to make the children as comfy as possible."
The runway closure has also prompted the army to join the hunt for the drone.
Specialist equipment has been deployed by the MOD (Ministry of Defence) to Gatwick airport to assist Sussex Police.
"We are there to assist and do everything we can," Defence Secretary Gavin Williamson told Sky News, declining to give the troops' exact role and adding that it followed a request from local police.
Gatwick, which is around 50km (30 miles) south of London, is the eighth-busiest airport in Europe and sits behind Mumbai as the world's busiest single runway air hub.
Inbound flights were diverted to other airports, including Paris, while easyJet, Gatwick's biggest operator, said it had cancelled all its flights in and out of the airport.
Around 10,000 passengers were affected on Wednesday night, and a further 110,000 who had been due to either take off or land at the airport on 760 flights on Thursday.
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Gatwick said it anticipated disruption to continue into Friday and urged travellers not to arrive at the airport before checking with their airline if their flight was cancelled.
It said: "Passengers due to fly from Gatwick should check the status of their flight with their airline and not travel to the airport if their flight is not confirmed."