(CNN) -- Kickstarter, a popular crowd-funding site, urged users to change their passwords Saturday after announcing that it had been hacked.
Kickstarter CEO Yancey Strickler said in a blog post that usernames, passwords, mailing addresses, e-mail addresses and phone numbers had been compromised by hackers, but no credit card information had been stolen.
"(W)e strongly recommend that you create a new password for your Kickstarter account, and other accounts where you use this password," Strickler said in the blog post. "We're incredibly sorry that this happened. We set a very high bar for how we serve our community, and this incident is frustrating and upsetting."
Hackers "gained unauthorized access to some of our customers' data," but "there is no evidence of unauthorized activity of any kind on all but two Kickstarter user accounts," a news release said.
Kickstarter did not say how many accounts were compromised.
Law enforcement alerted Kickstarter to the hack Wednesday, according to the release. The site then "immediately closed the security breach," it said.
According to the website -- which allows people with products, projects and inventions to post their ideas and raise money for them by garnering donations from users -- 5.6 million people have pledged funding to 56,000 projects since its launch in 2009.