Image source, Twitter/PADozens of people were stuck inside the tunnel for hours after a train broke down.
The Eurotunnel Le Shuttle passengers were evacuated and walked along an emergency service tunnel.
The replacement train took them to the terminal in Kent.
The train's alarms went off and need to be investigated.
Sarah Fellows said the service tunnel was terrifying after the incident.
It was a disaster movie. You didn't know what was going on. We had to wait under the sea.
There was a woman crying in the tunnel and a woman who was travelling alone.
The passenger who did not want to be named said that several people were freaked out about being in the tunnel. We were stuck there for a long time.
Le Shuttle initially said on social media that a train had broken down, but later said it had not, and that investigations were needed.
The people were transferred in line with safety procedures and as a comfort measure.
A passenger said they were on the stopped train and contacted the radio station. The passenger said the tannoy system was malfunctioning.
People had to abandon their cars on the train and be escorted out on foot, according to a traveller.
There was light passenger traffic on the Folkestone side.
Customers were told not to go to the terminal on Tuesday.
Le Shuttle advised not to go to the terminal tonight due to the earlier train fault. Arrive after 6 am tomorrow.
Passengers and their vehicles are transported between Folkestone and Calais.
It has the longest underwater section of any tunnel in the world at 2 km.