A ransomware attack has targeted the central data systems of Paris’ Grand Palais and other museums in the Réunion des Musées Nationaux network, the Paris prosecutor’s office said Tuesday. Some of the venues in the network are hosting competitions for the Summer Olympics.

The attack, detected on Sunday, hit data systems used by around 40 museums across France.

Despite the breach, Paris authorities said Tuesday there has been no disruption to the Olympic events.

The Grand Palais is hosting fencing and taekwondo competitions, while the Château de Versailles, also part of the RMN network, is the venue for equestrian sports and the modern pentathlon.

The Paris prosecutor’s office has assigned the investigation to a subdivision, the Brigade for Combating Cybercrime, to determine the extent and perpetrators of the attack. Efforts are ongoing to secure and restore the affected systems.