Organizers of the PyeongChang Winter Olympics said Saturday that its servers were hacked by an unknown attacker during the opening ceremony on Friday.

The Organizing Committee for the PyeongChang Olympic and Paralympic Games said the cyber attack caused a malfunction with the Internet protocol televisions (IPTV) at the Main Press Center.

Organizers shut down the servers to prevent further damage which led to the closure of the Olympic Web site.  

During this period, people were unable to print out their reserved tickets to Olympic events. 

The Web site was restored around 8:00 a.m. Saturday. 

The perpetrator of the attack remains unknown.

The organizing committee put out a statement saying that some issues occurred on Friday but had no effect on the safety of any athletes or spectators during the opening ceremony.

It said it was investigating the cause and will share the findings.