Kickstarter on Saturday acknowledged a hack that occurred on Wednesday night, advising users to immediately change the passwords of their accounts. According to the company, “law enforcement officials contacted Kickstarter and alerted us that hackers had sought and gained unauthorized access to some of our customers’ data.” Kickstarter says that “no credit card data of any kind” was accessed by hackers, and there’s “no evidence of unauthorized activity of any kind on all but two Kickstarter user accounts.”

The personal data Kickstarter hackers were able to access includes usernames, email addresses, mailing addresses, phone numbers and encrypted passwords. The company notes that while passwords were not revealed, “it is possible for a malicious person with enough computing power to guess and crack an encrypted password, particularly a weak or obvious one.”

Kickstarter did not reveal any details about the purpose of the attack or the persons behind it.