France’s high-speed rail network was hit Friday with widespread and “criminal” acts of vandalism including arson attacks, paralyzing travel to Paris from across the rest of France and Europe only hours before the grand opening ceremony of the Olympics, writes AP.

French officials condemned the attacks as “criminal actions,” though they said there was no sign of a direct link to the Games, and prosecutors in Paris opened a national investigation saying the crimes could carry sentences of 15 to 20 years.

As Paris authorities geared up for a spectacular parade on and along the Seine River, 3 fires were reported near the tracks on the high-speed lines of Atlantique, Nord and Est, causing disruptions that affected hundreds of thousands of travelers. Among them were 2 German athletes in showjumping who were on a train to Paris to take part in the opening ceremony but had to turn back in Belgium because of the closures, and will now miss the ceremony.

French Prime Minister Gabriel Attal wrote on the social media platform X that France’s intelligence services have been mobilized to find the perpetrators.