A large section of a terminal at Gatwick Airport has been evacuated due to a security incident.
Passengers have been unable to enter the South Terminal since 10:55 GMT.
“Safety and security of our passengers and staff remains our top priority,” an airport spokesperson said.
Railway services are also not stopping at Gatwick Airport station until further notice.
The airport, in West Sussex, said the evacuation was a precaution while it continued to investigate.
“Passengers will not be able to enter the South Terminal while this is ongoing,” the spokesperson said.
“We are working to resolve the issue as quickly as possible.”
National Rail said no services would be calling at Gatwick Airport while police dealt with the incident.
A Southern spokesperson advised passengers not to travel to Gatwick.
“At present, the station and airport are being evacuated whilst the police are dealing with an incident,” they said.
“We would recommend delaying your journey until later this morning.”
Thameslink, Southern and Gatwick Express services are affected.
Laurence Kemball-Cook, who was due to fly Portugal, said he and his family faced delays of up to 90 minutes getting through security.
“We were sitting there waiting for a slightly delayed flight and one of the staff rushes over and says ‘you’ve got to evacuate right now’. So I sprinted down the corridor, picked up my partner and the baby, who were changing, and then they were rushing everyone out the main terminal,” he said.
“We are now waiting with no guarantees of when it’s going to leave.
"I can see the plan but it looks like the whole airport is shut and no-one, none of the police, will say anything to us.”
Local bus services have also been affected and are unable to run to Gatwick, according to Southern.
“We've also been advised of local road closures too, so if you are driving to the airport, please be aware of this when planning your journey,” a spokesperson said.