Eurostar passengers were evacuated onto the side of a train track after a fire at the Gare du Nord station in Paris caused disruption to the line.
Customers complained of overheated carriages as a heatwave caused temperatures to rise above 30C.
Six trains travelling between London and Paris and in the opposite direction were cancelled because of the incident, while five trains were left stranded on the line while the operator found out whether they could be returned safely to the Paris station
Authorities said a fire was started by vandals at the Garde du Nord in the French capital.
It also caused disruption to other services out of the station, including TGV trains.
SNCF said the fire caused by a “malicious incident,” without elaborating, The Telegraph reported.
A police official said the fire started in an electrical station and prompted power to be cut off to the rails immediately.