The hackers, police said, also obtained e-mail addresses and other personal information of people who made complaints about drug crimes, The Salt Lake Tribune reported.
Police are urging those who provided their e-mails through the Web site, slcpd.com, to change their passwords, especially those who used the same password to log in to the site as they use at home or work.
Initially, Salt Lake City Police spokesman Shawn Josephson said the site was not linked to information in police reports or other confidential documents.
Those who claimed to hack the site said in a Twitter post Wednesday they were able to obtain confidential information and provided a redacted citizen complaint as proof.
The police Web site, which police took offline Tuesday, allowed communication between the public and police.
While the site is down, the public can get access to police news at slcpd.blogspot.com.
The site had been hacked by a collective known as Anonymous.
Police said the group called the attack a response to an anti-graffiti paraphernalia bill in the state Senate.
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