A popular Japanese video-sharing platform, Niconico, is investigating a cybersecurity incident that forced the company to suspend its services.

The Tokyo-based company said on Monday that a “large-scale cyberattack” affected its services early on Saturday. Afterward, it temporarily shut down its live streaming platform and user channels “to minimize the impact” of the incident.

“We deeply apologize for the inconvenience caused to users and content providers who regularly enjoy our videos and live broadcasts,” the company said in a statement. It is currently investigating the incident “to grasp the full extent of the damage.”

As of Monday, the attack was still ongoing, Niconico said, adding that “it is difficult to provide any updates on future developments until safety can be ensured.”

Niconico is one of the largest video posting sites in Japan with nearly 1.43 million premium members, about 89 million active members, and 10,180 channels.

Niconico’s parent company, Japanese media giant Kadokawa, confirmed on Sunday that the incident also affected other platforms, including its official website and e-commerce website, likely due to “unauthorized external access” to servers. The company said it is investigating the attack with external experts and the police.

Niconico’s services remained unavailable as of late Monday, Tokyo time, with its website stating that it is “undergoing maintenance.” The company said that it is also working to rebuild its entire system to prevent future cyberattacks.

Niconico said that it will later inform its users about the results of the investigation and address questions about membership fees and rescheduled deadlines for live broadcasts.

It is not clear what type of cyberattack affected Niconico or if hackers asked for a ransom. Dwango, the company that runs Niconico under Kadokawa, hasn’t responded to a request for comments.

According to Niconico, no user credit card information has been leaked during the incident.