Question-and-answer site Quora announced Monday that a data breach may have compromised the personal information of about 100 million users.

The company discovered “a malicious third party” had gained access to their systems exposing private account information on Friday.

Quora has notified law enforcement officials of the breach and is investigating the exact cause, said CEO Adam D’Angelo in a company blog post.

“In addition to the work being conducted by our internal security teams, we have retained a leading digital forensics and security firm to assist us,” he said.

Personal user data including name, email address, encrypted password, and public questions, answers, and comments were exposed in the breach. Anonymous content was not affected.

While the investigation is ongoing and Quora believes it has identified the root cause, they have begun notifying users whose data was compromised. They are also logging users out of affected accounts and invalidating passwords.

Those who were affected will receive an email update.