Trains to and from Paris, including the international Eurostar service, were hit Friday by what authorities called a "massive attack aimed at paralyzing the network" just hours before the start of the Paris Olympics.
Fires were ignited at critical network nodes in the sabotage, announced officials of the national railroad system SNCF, according to the Associated Press.
Cable lines were burned and cut, damaging signal boxes, and fires were reported on the tracks of the high-speed lines of Atlantique, Nord and Est, AP reported.
The attacks disrupted travel for hundreds of thousands of people from within France and other European nations ahead of the opening ceremonies for the games.
Eurostar, which links Paris to London, Amsterdam and Lille in France, was canceling 25% of its train runs over the weekend and diverting the rest from the high-speed network.
There was no immediate word on who may have been responsible for the attacks.
Outgoing French Prime Minister Gabriel Attal said the criminal operation had a "clear objective: blocking the high-speed train network" with "massive consequences."
He said the arsonists strategically targeted the main train routes from the north, east and west toward Paris hours before the Olympics opening ceremony.
One of the planned attacks was interupted when suspicious railroad workers working the night shift on France's Paris-Marseilles southeast line called police, AP reported.
"These people left, of course, very quickly when they realized they were spotted. So, thank you to the railway workers," said SNCF CEO Jean-Pierre Farandou. "Unfortunately, we couldn't do it everywhere."
Repairs were being made as police investigators collected evidence and sought saboteurs, he said.
Frarandou had few other details.
Attal urged patience before attempting to assess blame for the attacks.
"The investigation is starting, I call on everyone to be cautious," he said. "What we know, what we see, is that this operation was prepared, coordinated, that nerve centers were targeted, which shows a certain knowledge of the network to know where to strike."
Last Sunday Paris police arrested a Russian chef in the city on suspicion of plotting with a foreign power to stage alleged "large scale" acts of "destabilization" during the Olympics, the Guardian reported.
It wasn't immediately clear if the Russian may have been linked to the train disruption.
