LONDON -- The group known as Anonymous said Saturday it has hacked into some 70 mostly rural law enforcement websites in the United States, a breach that one local police chief said had leaked information about an ongoing investigation.

The loose-knit international hacking collective posted a cache of data to the Web early Saturday, including emails stolen from officers, tips which appeared to come from members of the public, credit card numbers and other sensitive information.

Anonymous said it had stolen 10 gigabytes of data in all.

Tim Mayfield, a police chief in small-town Gassville, Ark., said that some of the material posted online -- pictures of teenage girls in their swimsuits -- related to an ongoing investigation, which he declined to discuss further.

Mayfield's comments were the first indication that the hack might be serious. Since news that some kind of an attack first filtered out earlier last week, various police officials dismissed it as nothing to worry about.

"We've not lost any information," was one typical response, given by McMinn County Sheriff Joe Guy to WDEF-TV in Tennessee on Tuesday.

But many of Guy's emails were among those leaked to the Web on Saturday, and others seen by The Associated Press carried sensitive information, including tips about suspected crimes, profiles of gang members and security training.

The emails were mainly from sheriffs' offices in places such as Arkansas, Kansas, Louisiana, Missouri and Mississippi. Most, if not all, of their websites were either unavailable or had been wiped clean of content.

Cyberattack on cops

Anonymous said in a statement that it was leaking "a massive amount of confidential information that is sure to [embarrass], discredit and incriminate police officers across the US."

The group added that it hoped the disclosures would "demonstrate the inherently corrupt nature of law enforcement using their own words" and "disrupt and sabotage their ability to communicate and terrorize communities."

The group also posted five credit card numbers it said it used to make "involuntary donations." At least four of the names and other personal details published to the Internet appeared genuine, although those contacted by The Associated Press said they did not know whether their financial information had been compromised.

Many calls to various sheriffs' offices across the country went unanswered or weren't returned Saturday, but several others confirmed that a cyberattack had taken place.

Although the hackers said the attack occurred days ago, many sheriffs first learned of its scope only when contacted by the AP.