Video report by ITV News Reporter Dan Rivers
Gatwick Airport is to remain closed overnight after more drone activity was reported "within the last hour", the airport's chief operating officer said.
The Army was drafted in to help tackle drones which have grounded planes at Gatwick Airport, causing chaos as the Christmas getaway begins.
More than 110,000 passengers have been affected after the airport was forced to suspended all flights due to drones spotted flying close to the runway.
The Ministry of Defence tweeted to say specialist equipment has been deployed to help police, as the hunt for the gadgets which were first spotted at around 9pm on Wednesday evening continued.
Speaking to reporters, Defence Secretary Gavin Williamson confirmed that Sussex Police had requested assistance from the Armed Forces.
Police had earlier ruled out shooting down the drone due to safety fears concerning stray bullets, even though armed officers were spotted near the runway by mid-afternoon on Thursday.
However late on Thursday Detective Chief Superintendent Tingley told ITV News taking the drones out with firearms were now "one of the options".
"There are a number of factors in terms of range, the height of the drone and the likely impact of us firing at the drone but that is a tactical option open to the gold commander who will make a decision based on the information available to them at the time," he said.
COO Chris Woodroofe told reporters on Thursday night: "The last 24 hours have been very difficult for the airport. 120,00 passengers were due to fly out between 9pm last night when we closed the airport and today and those passengers have not flown anywhere because we have drone activity. Within the last hour we have had drone activity.
"But let's be clear, my apologies to all those passengers who have seen this disruption from the criminal activity of these people who are purposely disrupting our airport and their travel so close to Christmas."
He had earlier insisted there were "no indications" it might be linked to terrorism.
After closing following the first sighting on Wednesday night, the runway briefly reopened at 3am – but just 45 minutes later it was shut again, with delays impacting more than 110,000 people.
Speaking to reporters, Supt Burtenshaw said: "Each time we believe we get close to the operator, the drone disappears; when we look to reopen the airfield, the drone reappears.
"I'm absolutely convinced it's a deliberate act to disrupt Gatwick Airport."
Why does a drone cause so much chaos?
Video report by ITV News Correspondent Rebecca Barry
Chris Woodroofe earlier slammed the "irresponsible" behaviour, saying that two drones had been seen flying "over the perimeter fence and into where the runway operates from".
He added that 20 police units from two forces were hunting for the pilot, but had earlier in the day deemed it too dangerous to shoot the drone down because of what may happen to the stray bullets.
Passengers faced delays to their travels as some flights were unable to leave the tarmac while others were diverted to alternative airports, both in the UK and overseas including Amsterdam and Paris.
Some people reported being left stuck on planes for several hours while they waited to find out what was going on.
Gatwick advised anyone flying from the airport, or collecting someone, to check the status of their flight.
A spokeswoman added that airlines were working to provide affected passengers with hotel accommodation or transport for those whose flights were diverted.
The ongoing incident has been widely condemned, with Theresa May's official spokesman calling it "irresponsible and completely unacceptable".
He added: "These drones have been flown illegally and the law couldn't be clearer that those found endangering aircraft could face up to five years in jail."
A cross-Whitehall meeting of officials was held at 3pm on Thursday, including staff from the Department for Transport, Home Office, the police and the Civil Contingencies Secretariat, to discuss the problem.
Meanwhile, during a debate in the House of Lords, aviation minister Liz Sugg agreed with suggestions that more stringent laws were needed to prevent such incidents in future.
"The disruption that these drones have caused is extensive... We are in close contact with Gatwick Airport as they work with the police to safely resolve the situation as quickly as possible," she said.
"These drones have been flown illegally and anyone endangering an aircraft could face up to five years in jail.
"We absolutely need to make sure that we introduce new laws to ensure that drones are used safely and responsibly."
Meanwhile, the Guild of Air Traffic Control Officers accused lawmakers of ignoring their repeated warnings over the danger of drones - saying that "business interests" had been prioritised instead.
In a statement, they said:
[This] level of disruption experienced is unprecedented and such an event will continue to be a threat until appropriate measures are taken.
Among those passengers to be hit by the delays and cancellations was Lyndsey Clarke from Southend-on-Sea, who said she was stuck on "the plane of living hell" for more than four hours after it was re-routed to Stansted.
The 27-year-old said passengers were then having to fork out for taxis back to Gatwick after they were finally allowed off the aircraft.
Luke McComiskie’s plane ended up in Manchester, and he described chaotic scenes as people tried to find their way home after more than three hours stuck on board.
The 20-year-old from Aldershot said: “We got told there would be some arrangements with coaches for us when we get out the terminal… it was just chaos and they had only two coaches and taxis charging people £600 to get to Gatwick.”
One pilot, who was diverted to Stockholm when the disruption began, described "chaos" as their arrival slot was pushed further and further back - adding: "This is why we do not like drones."
Joe Bond’s flight from Belfast was diverted to Birmingham, and he joked on Twitter: “From the sound of the stewards we might be staying here forever.”
He added: “Update. Got a free can of Coke and Pringles. Which has made the delay better.”
Oana Damian tweeted that her flight had been diverted to London Heathrow but no-one could disembark as there were no customs and ground handling operations in place to deal with the plane.
Honor Ireland wrote: “Landed at Stansted when we should be at @Gatwick_Airport due to a supposed drone sighting – car is at Gatwick, fantastic! #gatwickairport”
John Belo said: “Plane should have departed an hour ago from @Gatwick_Airport – captain confirmed there are reports of a drone in the area … still waiting.”
Taking to Twitter, Sussex Police asked anyone with information about the person or persons operating the drones to contact them via the 999 emergency number, quoting reference number 1350-19/12.