Shooting down a drone which has caused chaos at Gatwick Airport is a “tactical option” being considered by police.
The measure had previously been ruled out by Sussex Police, which cited concerns over “stray bullets”.
But with the airport expected to remain closed on Friday, Det Ch Supt Jason Tingley said the force would “do what we can to take that drone out of the sky”.
The Army has been deployed to assist the police operation.
Gatwick’s chief operating officer Chris Woodroofe said 120,000 passengers had been due to fly out since the airport closed its runway on Wednesday.
“We will review overnight whether there is any potential to open tomorrow,” he said.
“But we are working up contingency plans all the way through to no flights tomorrow.”
He said the situation remained “fluid”, as the drone had been spotted again less than an hour earlier.
Police have been locked in a game of cat and mouse with the drone, and have received about 50 reports of the device being flown near the airfield since Wednesday evening,
No arrests have been made, and the airport is expected to be closed for the “foreseeable future” while the hunt for the operator continues.
Those due to travel on Friday have been urged to check with their airline before arriving at the airport.
The number of aircraft incidents involving drones has grown dramatically in the past few years, as the popularity of the devices has increased.
In 2013 there were zero incidents, compared to almost 100 last year.
Mr. Grayling said the events at Gatwick are “not something that’s not been experienced in this country before”, even though drones have been a problem elsewhere in the world.
The government was now looking to “go further” with drone-control, he said, including considering age-limits for users.
He added: “Anyone who tries to do the same [as at Gatwick] again, should expect to go to jail for a long time.”
The UK Airprox Board assesses incidents involving drones and keeps a log of all reports.
In one incident last year, for example, a pilot flying over Manchester saw a red “football-sized” drone passing down the left hand side of the aircraft.
In another, a plane leaving Glasgow narrowly missed a drone. The pilot in that case said the crew only had three seconds of warning and there was “no time to take avoiding action”.
About 10,000 passengers were affected overnight on Wednesday and Gatwick said 110,000 people were due to either take off or land at the airport on Thursday.
Incoming planes were diverted to other airports including London Heathrow, Luton, Birmingham, Manchester, Cardiff, Glasgow, Paris and Amsterdam.
Crowds of travellers spent the morning waiting inside Gatwick’s terminal for updates, while others reported being stuck on grounded planes for hours.
