Los Angeles police said they were investigating how the Social Security number, address and a credit report of the police chief ended up on the site. The site also posted the same information about FBI Director Robert Mueller; the bureau said it was aware of the site but declined to say whether it was investigating.
The site also targeted stars such as Beyoncé, Ashton Kutcher, Kim Kardashian and Paris Hilton. Info posted about vice president Joe Biden and former Secretary of State Hillary Clinton did not include credit reports but included addresses and other sensitive information.
Social Security numbers posted on Gibson, Jay-Z and others matched records in public databases.
The site, which bears an internet suffix originally assigned to the Soviet Union, expanded throughout the day on Monday to add entries on Britney Spears, former vice presidential candidate Sarah Palin and others.
It did not state how the information was obtained or why the 11 people targeted on the site were selected, describing the records only as "secret files".
A Twitter profile linked to the site and created after its existence was first reported by celebrity website TMZ included an anti-police message in Russian.
Several of the purported credit reports appear to have been generated last week.
Representatives for each person targeted either declined to comment on the accuracy of the information that was posted, or they did not return messages seeking comment.
Los Angeles police Commander Andrew Smith said the LAPD was investigating the posting of Beck's information and would also investigate the posting of info on any celebrities who live in the city.
He said confidential information on top police officials has been posted online at least twice before.
"People get mad at us, go on the internet and try to find information about us, and post it all on one site," Smith said.
"The best word I can use to describe it is creepy," he said about the practice known as doxxing. "It's a creepy thing to do."
Frank Preciado, assistant officer in charge at the LAPD online section, said the postings are also illegal. He said the information was likely taken from what is supposed to be a secure database of city employees.
Several of the pages featured unflattering pictures of the celebrities or government officials whose information was posted.
The site's page on Los Angeles Police Chief Charlie Beck includes a taunting reference to former officer Christopher Dorner, who apparently committed suicide after he killed four people during a multi-day rampage.
Beck's page included the message "#YouCantCornerTheDorner" and an image of a woman protesting police corruption.
While government officials often have to disclose details on their finances - and celebrity divorces sometimes feature public financial data - the information posted online exceeds those disclosures.
Social Security numbers are rarely included in public records anymore because they can be used for identity theft.