Olympic officials have confirmed that a cyber attack took place during the event’s opening ceremonies in Pyeongchang, according to Reuters. The organizers say that while television and internet access was affected, it “it had not compromised any critical part of their operations.”

According to reports, internet access and Wi-Fi shut down on Friday during the game’s opening ceremonies. The website for the games also went down, preventing attendees from printing out tickets. Pyeongchang organizing committee spokesman Sung Baik-you confirmed that an attack took place, but that the issues have since been resolved. He also said that investigators wouldn’t reveal the source of the attack.

The games have already come under attack from hackers: Last month, McAfee said that it detected attacks in the months leading up to the games, in the form of malicious e-mails sent to Olympic officials. The company warned that further attacks were likely. Officials have worried about such attacks coming from North Korea amidst political tensions with South Korea, and Russia following the country’s ban from the games due to a systematic doping scheme.