Update: TPM's Josh Marshall confirms attack

Update 2: TPM posts statement on the attack

Update 3: Service returned to TPM as of 1 p.m. ET. Here's publisher Josh Marshall's explanation of what happened.

On Friday morning, the political website Talking Points Memo posted mug shots of several individuals arrested for their alleged connection with denial of service attacks carried out by the hacktivist group Anonymous.

TPM tweeted at the time, "We sincerely hope our site doesn't go down for posting this," but precisely that appears to have happened by Friday afternoon.

At 5:23 PM EST, the website National Confidential reported that TPM was offline, but then added four minutes later that the site was back. However, over the course of several attempts between 5:30 and 6:00, Raw Story was unable to get the main TPM page to load.

A page at the TPM site with the slide show of mugshots did load, but without the pictures. Its headline reads "Anonymous Unmarked," and a caption at the bottom explains, "Federal authorities in July arrested 16 alleged 'hackivists' they said were involved with the group Anonymous. Most of the defendants were accused of launching an attack on PayPal for disabling Wikileaks' account. Thanks to a Freedom of Information Act (FOIA) request, TPM has exclusively obtained their mugshots."

The same images are available at Gawker, however, with no sign of attempted interference. This might suggest that whatever problems TPM is experiencing are purely coincidental.

In addition, Raw Story was unable to find anything from Anonymous taking credit for an attack and just a single tweet referring to the mug shots at the AnonyOps Twitter account -- one of several associated with Anonymous. Although posted at about 5:30, after TPM had already gone down, it merely states, "Here are the 'anonymous' mugshots. Look at these dangerous terrorists. *zomg* /sarc."

Update: Shortly before 8:00 PM, Talking Point Memo's Josh Marshall twittered, "TPM has been offline since 5pm & Yes I can confirm its a DDOS attack. We have no direct proof of who is behind it. However,"

Shortly before 9:30, a statement on the attack went up at TPM's Facebook page. It read, in part, "We have no direct evidence of who is behind the attack. Still, given that Anonymous’s signature has been denial of service attacks, the logical inference is as apparent to us as anyone else.

"TPM is dedicated to bringing our readers the news. So we are mobilizing all our technical and legal resources to restore the site as soon as possible. We are also in contact with law enforcement. We will also shortly launch a temporary alternative site where readers can get the latest updates on the news of the day from our reporters.

"We are lucky enough to live in a country where the risks and consequences of practicing journalism are usually quite light. Certainly compared to other countries. This episode is trivial in comparison to what numerous journalists have suffered in other countries when people retaliate over what is reported about them. Still, even in such minor forms, reporting the facts about criminal activity and the news of the day is not without consequences. But we believe in what we do. So we can take it."