Flights into and out of Britain's Gatwick Airport were halted for hours Thursday after drones were spotted for two days in a row over the airfield, and authorities said tens of thousands of travelers would be affected well into Friday.

"There are 110,000 passengers due to fly today and the vast majority will see cancellation and disruption," said Chris Woodroofe, Gatwick's chief operating officer. More than 750 flights were scheduled to fly into and out of Gatwick Thursday, The Associated Press reported.

Woodroofe didn't expect the airport to operate smoothly for some time, as the cancelations would be compounded by the rush of the holiday weekend.

"Realistically it’s going to take several days to recover," Woodroofe said.

European air-navigation agency Eurocontrol announced Thursday afternoon that all flights would be canceled through at least 6 a.m. GMT Friday (1 a.m. ET). Gatwick officials urged travelers not to come to the airport Thursday or Friday without checking the status of their flights.

Gatwick is Britain's second busiest airport with 46 million people passing through in the past 12 months, compared with Heathrow's 80 million, according to the airlines.

The airport first closed its runway Wednesday night after two drones were spotted over the airfield. It reopened for less than 45 minutes before closing again at 3:45 a.m. GMT Thursday (10:45 p.m. ET Wednesday) after more drones were spotted, according to airport officials.

An information board announces flight disruption at London Gatwick Airport, south of London on Dec. 20, 2018 after all flights were grounded due to drones flying over the airfield. Glyn Kirk / AFP - Getty Images

The latest drone was seen over the airport at 8:45 a.m. GMT (3:45 a.m. ET), according to Sussex Police.

As authorities searched for the operators of the drones, police said there was no indication the incident was terror-related but rather a "deliberate act to disrupt the airport."

"I’m talking about an act that is deliberately seeking to affect the tens of thousands of passengers that wanted to fly from Gatwick today, this close to the Christmas period," Woodroofe said. "It’s them who have paid the price of this deliberate act."

The airport's CEO, Stewart Wingate, echoed that the drone deployment was a "highly targeted activity which has been designed to close the airport and bring maximum disruption in the run up to Christmas."

He apologized to customers and said the aviation industry needed to work with authorities to prevent this "criminal" behavior from happening in the future.

"It cannot be right that drones can close a vital part of our national infrastructure in this way," Wingate said. "This is obviously a relatively new technology and we need to think through together the right solutions to make sure it cannot happen again."

He said he couldn't say with certainty when airport service would return to normal.

Katy Day, who lives in Cambridge, was trying to get home to her family in Orlando, Florida, for the holidays. When she got to Gatwick, she couldn't even check her bags.

"There was tons of families with small kids and everybody was sitting on the floor with their bags," Day told NBC News. “Everywhere I went I had to take my bags with me and it was really hard to move cause it was so crowded.”

"It's Britain, so it was chaos. But it was a very chilled chaos, a very stiff-upper-lip chaos,” Day said. She was eventually shuttled to Heathrow where she was waiting on Thursday afternoon for a flight to Orlando.

While some travelers already at Gatwick waited, others whose flights were scheduled to land there were diverted to Heathrow and other airports, including in Manchester and Birmingham.

Luke McComiskie, who landed in Manchester, more than 160 miles away from London, told the AP that the situation "was just chaos, and they had only two coaches (buses) and taxis charging people 600 pounds ($760) to get to Gatwick."

EasyJet, a major airline operating out of Gatwick said they were providing ground transportation, hotel accommodations or reimbursements for people who were diverted away from Gatwick.

As sales of drones have risen, aviation experts have warned that a drone colliding with a plane could have disastrous results.

Flying a drone near an airport could result in up to five years in prison in the U.K.