Gatwick Airport says the North Terminal has been evacuated "due to an incident".
The airport said it was a "precautionary measure".
Due to an incident - the North Terminal has been evacuated as a precautionary measure. Extra staff on-site looking after passenger welfare
Gatwick Airport's North Terminal has been evacuated because of a "suspect package", BBC London says it has been told by Sussex Police.
Gatwick Airport's North Terminal has reportedly been evacuated.
It comes amid heightened security following a series of deadly terror attacks in Paris.
Gatwick Airport representatives were not immediately available for comment.
Connor Gillies, a reporter for Capital FM, tweeted a picture showing floods of people making their way outside the terminal.
Gatwick Airport has been evacuated...
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A fire broke out at a Gatwick Airport car park on Wednesday evening.
The fire started near a drop-off point at the north terminal and caused temporary disruption to the airport's shuttle service.
No one was understood to have been injured in the fire.
A Gatwick Airport spokesman said it had been extinguished but the cause remained unknown.
The discovery of oil reserves discovered in the Gatwick airport area has been hailed as 'significant' but analysts have been more cautious.
While the chairman of UK Oil & Gas Investments claimed there were 158 million barrels a square mile over a possible 1,100 square miles others questioned the figures.
ITV News business editor Joel Hills reports.
The extent of the oil reserves discovered near Gatwick Airport have been called into question by a specialist in petroleum science.
Professor Alastair Fraser of Imperial College London told ITV News he thought the number of barrels that UK Oil & Gas Investments said lay in the Weald Basin was "probably a little bit exaggerated on the high side".
He added that the reserves would only become "significant" once the oil could be brought to the surface and at "flow rates that are commercial".
Prospectors have made the biggest oil discovery in the UK in 30 years - and say the true amount sitting underneath the south of England could be an unprecedented tens of billions of barrels.
The substance has been found near Gatwick - but some analysts are sceptical about how much of it can be extracted.
ITV News Science Correspondent Alok Jha reports:
To gleefully rub your hands at a new fossil fuel discovery you need to turn the clock back to the 19th century and ignore everything we have learnt about climate change since.
We already have more than enough coal, oil and gas reserves to fry the planet. Dotting the English countryside with drilling rigs and pipelines to squeeze the last drop of oil out of Britain doesn't make any sense.
It's time we uncoupled our economy from the dangerous rollercoaster of fossil fuels and invested in the clean technologies that can provide safe and cheap energy for decades to come.
David Lenigas, Chairman of UK Oil & Gas Investments, has spoken to ITV News about the firm’s discovery of oil reserves near Gatwick Airport.
He told Business Editor Joel Hills: "It’s a very significant discovery, 158 million barrels a square mile. The Weald Basin itself is 1,100 square miles, we’ve got 55 square miles and its pervasive.
“It’s like a big sponge, 1,500 ft thick with vast amounts of oil in it with three big limestones that you can effectively suck the oil out of the sponge. It’s a great find. There’s a lot more work to be done to bring it into proper production but eventually this will be a very key part of Britain’s strategic energy resource.
When asked about the vast difference in the oil potential projections of UKOG and the British Geological Survey for the area - who estimated between shale oil resources of 2.2-8.5 billion barrels - Mr Lenigas said people should believe the "last well that was drilled..(which was his company's) because drill holes don't lie."