France's high-speed rail network experienced coordinated arson attacks early Friday, paralyzing train travel to Paris for 800,000 people, including Olympic athletes. The fires, set in critical signaling cables, targeted remote locations to maximize disruption. French authorities have mobilized intelligence services to find the perpetrators, with speculation ranging from ultra-left groups to foreign interference by Iran. Despite the chaos, the Olympic opening ceremony proceeded as planned. The SNCF has worked to restore services, with most lines expected to return to normal by Monday, although delays and cancellations persist. Security measures have been increased, including ground and air surveillance, to prevent further attacks.