Gatwick Airport (CNN) Two people were arrested late Friday as part of an ongoing investigation into the "criminal use of drones which has severely disrupted flights in and out of Gatwick Airport" at the peak of the holiday travel season.

Police did not provide any details about the suspects. Sussex Police Superintendent James Collis said the investigation was not over.

"The arrests we have made this evening are a result of our determination to keep the public safe from harm," he said. "Every line of inquiry will remain open to us until we are confident that we have mitigated further threats to the safety of passengers."

The airport aims to run a full schedule of flights on Saturday but warned travelers to expect some delays and cancellations. Passengers were advised to continue checking the status of their flights with their airline before setting out.

There are 757 flights scheduled for Saturday, carrying more than 124,000 passengers, an airport spokesman said.

Flights from Gatwick were briefly suspended again on Friday after another reported sighting of a drone, leaving thousands of people stranded at the facility.

The latest closure came after more than 32 hours of complete shutdown due to repeated drone sightings Wednesday into Thursday.

An airport spokeswoman told CNN officials were made aware of the latest unconfirmed sightings at about 5:20 p.m. (12:20 p.m. ET) Friday and closed the runway as a precaution. Flights in and out of the airport south of London later resumed.

In a statement, the spokeswoman said: "While we investigated, airfield movements were suspended. This was a precautionary measure as safety remains our main priority."

The airport said on Twitter that it was trying to respond to an unprecedented number of tweets. "We apologize for the continued disruption today," it wrote.

Thousands of people have been stranded at the airport as their flights were canceled or delayed. Arriving flights have been diverted to other airports around the UK or even as far afield as Paris and Amsterdam. About 1,000 flights have been canceled or diverted in total, affecting up to 150,000 passengers since Wednesday evening.

Many more were due over the weekend, with 2.6 million people expected to pass through Gatwick over the Christmas-New Year period.

"Passengers should expect some delays and cancellations as we continue to recover our operations following three days of disruption and are advised to check with their airline before traveling to the airport," an airport spokesman said.

Passengers wait in the South Terminal building at London Gatwick Airport after flights resumed Friday.

What's being done?

The Ministry of Defence said Thursday that specialist equipment had been deployed to assist Sussex Police in their efforts. Sussex police assistant chief constable Steve Barry was not able to go into detail about what that equipment might be.

Police will also consider shooting the drone down, Barry said. That option was previously put aside over concerns for stray bullets.

"The issue is whether or not, in relation to the threat that is posed, it's proportionate. As time has gone on and the level of disruption and threat increased, obviously that option has come back into availability," he said.

The airport tweeted Friday that the military measures in place were reassuring enough to reopen the airfield.

It seems unlikely that affected travelers will be able to claim compensation from their airline. The UK Civil Aviation Authority issued guidance advising that "given the reasons for the current disruption" at Gatwick, the body "considers this event to be an extraordinary circumstance." This means airlines are not obliged to pay compensation.

The @UK_CAA is offering advice to passengers impacted by the disruption at Gatwick Airport.



Please visit the following website to find a leaflet on your rights as a passenger: https://t.co/9hxLyyJBvB.#Gatwick #Gatwick_Airport pic.twitter.com/ljUaFDKcMo — UK Civil Aviation Authority (@UK_CAA) December 20, 2018

Transport Secretary Chris Grayling told the BBC the burden should fall on travel insurance companies. "It goes beyond what the airlines are responsible for, this should be covered under travel insurance policies but we will talk to the insurance industry today to make sure they treat claims reasonably."

Who's behind this?

Sussex Police had said the disruption was deliberate, but unlikely to be terror related. Beyond that, the motivations of the perpetrator or perpetrators remain unclear.

While some UK media have reported that environmental protesters may be behind the incident, no group has come forward to claim responsibility, nor has any manifesto or explanation been released.

What appears clear is that the perpetrators were well prepared. Police said the drone or drones being used were of "industrial specification."

Whoever is found to be behind the disruption could face up to five years in prison for endangering the safety of an aircraft.

Transport and aviation bodies have called for the laws on drone use to be tightened in the wake of the incident, with pilots' union Balpa saying an exclusion zone around airports should be extended from 1 kilometer to 5 kilometers (3 miles).

"It is now obvious that that must happen urgently. This incident also reinforces the need for registration and licensing of operators so that the police can track and trace drones," spokesman Brian Strutton said.