Flights are resuming at England's Gatwick Airport hours after a fresh drone sighting forced a second major shutdown of the transportation hub — stranding thousands during one of the busiest travel weeks of the year.

Authorities had reopened the airport earlier Friday after a 36-hour closure scrambled Christmas plans for more than 120,000 travelers. The closure came as a result of drones being spotted around the airport, potentially putting planes in danger.

Just 11 hours after allowing some flights to resume, however, planes were temporarily grounded again with a new report of a drone buzzing worryingly close to the runway — despite the presence of military and police snipers mobilized to shoot it down.

"We have learnt quite a lot over the last 36 hours in terms of the capabilities, the options that we need to mitigate if this is a threat," Assistant Chief Constable Steve Barry of Sussex Police told NBC News Friday morning.

"But the other thing that we have learnt is that despite the significant disruption to passengers and I've seen the distress, I've read the comments on social media, their safety has been the prime responsibility of both the airport and the police in dealing with this situation," he said.

Flights have now resumed. Airfield movements were suspended while we investigated this as safety remains our main priority. The military measures we have in place at the airport have provided us with reassurance necessary to re-open our airfield. — Gatwick Airport LGW (@Gatwick_Airport) December 21, 2018

The reopening comes after high-tech military technology, including an Israeli-developed radar system, was brought in to track the drones and jam the signals from the operator, England's Sky News reported.

"The military measures we have in place at the airport have provided us with reassurance necessary to re-open our airfield," a representative for Gatwick tweeted Friday in announcing the second resumption of flights.

Police officers survey Gatwick Airport runways as flights resume on Dec. 21, 2018. Jack Taylor / Getty Images

Flying drones within 1 km (0.6 mile) of a British airport is a crime punishable by five years in prison.

Police are investigating a number of potential suspects, but said there was no evidence that the drones are part of a terror attack, Reuters reported.

But ever since the first flights were grounded at 21:03 GMT on Wednesday after two drones were first spotted, it has become clear that the drones are part of an intentional disruption campaign, authorities said. And disrupting is exactly what it did, with thousands of passengers forced to sleep in the airport waiting to resume their travel plans.

“It has ruined the holiday for the whole of our family,” stranded passenger Anne Cracknell said late Thursday. “We've saved up all year to get this holiday and it’s just been shattered, all for somebody flying drones.”

Gatwick is Britain's second busiest airport with 46 million people passing through in the past 12 months, according to airline data.

This week's shutdown marks the worst disruption for Gatwick since 2010, when an ash cloud from an Icelandic volcano grounded flights across Europe.

The act of sabotage has also drawn attention the potential dangers to aviation that come with the proliferation of drone technology.

"There is a large piece of work that needs to be done not just across the U.K. aviation industry but across the international aviation industry," Chris Woodroofe, Gatwick Airport's chief operating officer, said Friday morning.

"Working with technology providers, to get ourselves to a place where we can better counteract the risk of drones to airports. This unprecedented act from the last 36 hours demonstrates that there is an awful lot more work to do."