A “coordinated sabotage” has paralyzed France’s high-speed train network, impacting a quarter million travelers. The number is set to rise to 800k by the end of the weekend, ahead of the opening ceremony of the Paris Olympics.

In a post on X, French state railway company SNCF described the overnight fire and cutting of critical signal cables near the tracks in Courtalain, northern France, impacting services to Paris, as a “massive attack aimed at paralyzing the high-speed line network.”

SNCF said a “large number of trains were diverted or canceled” and requested that “all travelers who can postpone their trip and not go to the station.”

The French prime minister has pledged to “find and punish” those responsible for the attack on critical infrastructure.