Saboteurs struck France’s TGV high-speed train network in a series of pre-dawn attacks across the country, causing travel chaos and exposing security gaps ahead of the Paris Olympics opening ceremony later on Friday.

The coordinated sabotage took place as France mounted a massive security operation, opens new tab involving tens of thousands of police and soldiers to safeguard the capital for the sporting extravaganza, sucking in security resources from across the country, Reuters reported. 

SNCF, the state-owned railway operator, said vandals had damaged signal substations and cables along the lines connecting Paris with cities such as Lille in the north, Bordeaux in the west and Strasbourg in the east. Another attack on the Paris-Marseille line was foiled.

There was no immediate claim of responsibility for the attacks on the high-speed rail network, which is a source of national pride for many in France. Two security sources said the modus operandi meant initial suspicions fell on leftist militants or environmental activists, but they said there was not yet any evidence.

The Paris prosecutor’s office said the probe would be overseen by its organised crime office, with the anti-terrorist sub-directorate (SDAT), a branch of the judicial police that typically monitors hard-left, extreme-right and radical environmental groups, coordinating investigations.

Prime Minister Gabriel Attal declined to speculate about the possibility of such groups being behind the sabotage.

“What we know, what we see, is that this operation was prepared, coordinated, that nerve centres were targeted, which shows a certain knowledge of the network to know where to strike,” he said.

The coordinated strikes on the rail network fed into a sense of apprehension ahead of Friday evening’s Olympics opening ceremony in the heart of Paris. Operations at the Basel-Mulhouse airport on France’s border with Switzerland were briefly suspended due to a bomb alert.

International Olympic Committee President Thomas Bach said he had full confidence in the French authorities. “I don’t have concerns,” he told reporters at the Olympic Village.

Spectators took their seats along the banks of the River Seine for the opening ceremony, with around 300,000 people expected to watch the athletes parade by on a flotilla of barges and riverboats, with billions tuning in on TV.

France has deployed 45,000 police, 10,000 soldiers and 2,000 private security agents to secure the ceremony, with snipers on rooftops, and drones in the air. But while the capital is locked down, security elsewhere in the country is lighter.

The attacks hit signalling installations on the Atlantic, Northern and Eastern high-speed lines with fires set off by explosive devices, the SNCF said.

Traffic would resume as normal on the eastern line from Saturday morning, the rail operator said, while trains heading northwest to Brittany and the southeast should be running closer to schedule by Saturday. On northern routes, 80% of high-speed trains were operating with one to two hour delays, it said.

Eurostar’s high-speed services linking London and Paris were forced onto slower lines while Germany’s Deutsche Bahn warned of disruption to long-distance services.

At the Gare de L’Est, Xavier Hiegel, 39, said he was trying to get home for the weekend and could not believe that people would want to harm the Olympics.

“The Games bring jobs so this really is nonsense. I hope the people responsible will be found and punished,” he said.

SNCF chief Jean-Pierre Farandou said some 800,000 customers had been impacted ahead of a busy weekend for French holidaymakers. Thousands of rail staff had been deployed to repair the damage.

“This attack is not a coincidence, it’s an effort to destabilise France,” Valerie Pecresse, president of the Paris region, told reporters.

Paris 2024 said it was working closely with the SNCF to assess the situation. The attacks will make it tougher for people travelling to Paris for Olympic events.

“It’s a disaster,” said Parisian Brigitte Dupont. “Today is the opening of the Olympic Games, a huge event that was supposed to be magnificent, and this is spoiling people’s joy.”