Kickstarter, a web site that serves as a funding platform for creative projects, said on Saturday that malicious hackers gained unauthorized access to its systems and accessed user data.

“On Wednesday night, law enforcement officials contacted Kickstarter and alerted us that hackers had sought and gained unauthorized access to some of our customers' data,” Yancey Strickler, Kickstarter’s CEO, wrote in a security notice. “Upon learning this, we immediately closed the security breach and began strengthening security measures throughout the Kickstarter system.”

According to Strickler, customer information accessed by the attacker(s) included usernames, email addresses, mailing addresses, phone numbers, and encrypted passwords.

“Actual passwords were not revealed, however it is possible for a malicious person with enough computing power to guess and crack an encrypted password, particularly a weak or obvious one,” Strickler said.

The company said via Twitter that "old passwords used salted SHA1, digested multiple times. More recent passwords use bcrypt."

Strickler said that no credit card data was accessed by the attackers, and that so far only two Kickstarter user accounts have seen evidence of unauthorized activity.

Kickstarter did not say how many user accounts were affected in the breach, but the company says that since launching in 2009, more than 5.6 million people have pledged $980 million, funding 56,000 creative projects through its platform.

“As a precaution, we strongly recommend that you create a new password for your Kickstarter account, and other accounts where you use this password,” the advisory suggested.

“We have since improved our security procedures and systems in numerous ways, and we will continue to do so in the weeks and months to come,” Strickler wrote. “We are working closely with law enforcement, and we are doing everything in our power to prevent this from happening again.”

*Updated with additional details on password encryption.