Despite speculation that mystery hacker-group "Anonymous" is behind it, the NSA has denied their official website being down is the result of a cyberattack.

The National Security Agency's website, nsa.gov, has been down the better part of the afternoon, and people have been speculating it's "Anonymous."

Gizmodo reports that the site is suffering from a distributed denial of service (DDoS), when hackers overtake computers and direct them to overload a web server.

The site went down shortly after 3 p.m., and at the time of this post still was not back up.

Brian Fung, the tech reporter for the Washington Post, tweeted that he spoke with an NSA spokesperson, who said that they were looking into the outage, but refused to say if it was the result of a cyber attack.

Later, the NSA flatly denied the outage was the result of an attack. In a statement to Circa, an NSA spokesperson said, "NSA.gov was not accessible for several hours tonight because of an internal error that occurred during a scheduled update. The issue will be resolved this evening. Claims that the outage was caused by a distributed denial of service attack are not true."

As Gizmodo points out, it's not wholly clear that Anonymous is behind the attack, or that the NSA's website was attacked at all. And the fact that it took at least an hour for people to start linking the outage to anonymous is a little suspicious.

Anonymous tacitly acknowledged some level of involvement on Twitter.