Passengers have faced "chaos" with long queues and delays after part of Manchester Airport was evacuated.
People were told to leave Terminal Three by armed police and the fire service at about 06:00 BST on Thursday.
Police said an alarm was mistakenly activated by a passenger and the airport added that "everyone was back inside" the building.
An airport spokesman said: "There was a brief evacuation in a small part of the terminal building due to one of the red alarm panels being set off.
"Process dictates the area is evacuated but everyone is now already back in," he added.