Sensitive electronic files from America's biggest police union were posted online this week after a hacker breached the Fraternal Order of Police website. The ill-gotten dump includes officers' names and addresses, message board posts bashing Barack Obama, and details of eyebrow-raising contracts made between the union and city authorities.

The Fraternal Order of Police, or FOP, describes itself as "the world's largest organization of sworn law enforcement officers, with more than 325,000 members in more than 2,100 lodges."

"We have learned today that our data system has been hacked by the Group known as Anonymous," read a Facebook post Thursday from FOP president Chuck Canterbury. The attack "appears to have originated outside of the United States," the statement continued.

Further reports indicate the attack was traceable to an IP address in the UK.

From the Guardian's coverage:

The Fraternal Order of Police (FOP), which says it represents about 330,000 law enforcement officers across the US, said the FBI was investigating after 2.5GB of data taken from its servers was dumped online and swiftly shared on social media. The union's national site, fop.net, remained offline on Thursday evening. "We have contacted the office of the assistant attorney general in charge of cyber crime, and officials from FBI field offices have already made contact with our staff," Chuck Canterbury, the FOP's national president, said in an interview.

Here's a mysterious blog post about the data dump's origins.

The FBI hasn't yet commented, but they're said to be investigating the breach.