Gatwick advised anyone flying from the airport, or collecting someone, to check the status of their flight.
Social media users spoke of flights being forced to head to other United Kingdom airports, including London Heathrow, Luton and Manchester.
He said there were two drones which had been seen flying "over the perimeter fence and into where the runway operates from".
Gatwick's chief operating officer Chris Woodroofe said drones had been spotted over the airport as late as 7am this morning.
According to the airport's Twitter account, as of the time of publication, the airport remained closed. A police helicopter was dispatched to track down the vehicle and its operator, so far without success.
Here we look at the law surrounding drones.
Any problem at Gatwick causes a ripple effect throughout Britain and continental Europe, particularly during a holiday period when the air traffic control system is under strain.
Some passengers at Gatwick have reportedly had to wait for more than two hours because of the suspension.
Gatwick first closed Wednesday night at around 9 p.m. (2100 GMT) when drones were sighted.
A major worldwide airport in Britain was forced to ground flights after reports of drones flying over the airfield, the airport said on Thursday.
Passengers due to take off reported planes being stuck on the Tarmac for more than an hour.
Richard Hargreaves' easyJet flight was redirected to Birmingham, with those on board waiting to fly back to Gatwick.
It is unclear when flights will be allowed to leave or arrive at Gatwick today. "Which has made the delay better".