Dozens of people were left stranded for hours inside the Channel Tunnel after a train from Calais to Folkestone appeared to have broken down.
Footage emerged showing Eurotunnel Le Shuttle passengers being evacuated through an emergency service tunnel after having to abandon their vehicles.
They were eventually transferred to a replacement train and taken to the Folkestone terminal in Kent.
Le Shuttle said the train’s alarms went off and this needed to be investigated.
“The service tunnel was terrifying,” said Sarah Fellows, 37, from Birmingham to PA news agency after the incident on Tuesday evening.
“It was like a disaster movie. You were just walking into the abyss not knowing what was happening. We all had to stay under the sea in this big queue.
“There was a woman crying in the tunnel, another woman having a panic attack who was travelling alone.”
Another passenger, who did not want to be named, told PA: “Several people were freaking out about being down in the service tunnel, it’s a bit of a weird place… We were stuck down there for at least five hours.”
Le Shuttle, which transports vehicles through the tunnel, initially said on Twitter a train had broken down, but later added to the BBC that a train had not actually broken down, but the alarms going off meant investigations were needed.
All those on board were transferred at 20:22 BST (19:22 GMT) “in line with safety procedures and as a comfort measure”, Le Shuttle said.
A passenger contacted the BBC before 17:45 saying they were on the train which had stopped. The passenger complained of poor communication, with the tannoy system not working properly.
Another traveller tweeted that people had to abandon their vehicles on the train and were being escorted out on foot.
The Le Shuttle spokesperson later said that passenger traffic was light on the Folkestone side.
But customers travelling from Calais were advised not to travel to the terminal on Tuesday night.
“Due to the earlier train fault, we advise you not to travel to the terminal tonight,” Le Shuttle added. “Please arrive after 6am tomorrow.”
The service transports passengers and their vehicles between Folkestone and Calais.
At 37.9 kilometres (23.5 mi), it has the longest underwater section of any tunnel in the world.