Two people were temporarily detained by police after reports of a suspicious package meant Gatwick Airport’s South Terminal was evacuated.
The South Terminal, one of two at the airport, was shut at 10:55 GMT on Friday while an explosive ordnance disposal team “made the package safe”.
Sussex Police confirmed this afternoon that two people were detained but have since been allowed to continue with their journeys.
The terminal is now reopening for passengers, who are being warned of continuing delays and cancellations.
Earlier on Friday, thousands of stranded passengers were left waiting outside the terminal in near-freezing temperatures, with many saying they had no idea what was going on.
“No-one seems to know what they are doing,” said John Mather, who flew into the South Terminal from Costa Rica during the closure.
“We were then bussed to the North Terminal, where we went through immigration and collected our bags. [We had] no help whatsoever from airport or security staff.”
Mr Mather, who lives in Croydon, said that because the trains were not stopping at Gatwick, he would be forced to walk to the station in Horley – more than half an hour away.
“It’s hopeless, I’m stuck here,” he said.
Trains have since resumed calling at Gatwick.
Another stranded passenger was Gabriele Lecce, who had been hoping to fly to Rome but was told there was an issue when he arrived at departures.
“Fifteen minutes later, we saw the police coming and they evacuated us – we’re freezing out here,” he told the BBC.
Many people have been forced to make alternative travel plans, like Emily Fisher and her three friends, who have paid £1,200 between them for new tickets to Budapest, travelling from Luton Airport instead.
“We got to [Gatwick] airport at 11:00, there were hundreds of people outside,” said Emily.
“They said the terminal was on lockdown but the people at the airport were telling us they didn’t know anything.”
Travel journalist Simon Calder said about 100,000 passengers were due to fly in and out of Gatwick Airport on Friday – half of those through the South Terminal.
Now, passengers say they are “cautiously optimistic” as they board shuttle trains to the South Terminal.
“Until we’re on the plane, we can’t relax,” said Alaia, 18, who is trying to get home to Barcelona.
“I’m worried that so many planes are delayed that some won’t actually take off.”
A spokesperson for Gatwick Airport said passengers should check the status of the flight with their airline.