The Central Intelligence Agency's website went offline last night in an apparent hacking attack.
The hacker group Lulz Security claimed responsibility for the attack. The group has claimed responsibility for recent attacks on the US senate, Sony, News Corp and the US public broadcasting system's television network.
Lulz Security has defaced websites, posted personal information about customers and site administrators, and disclosed the network configurations of some sites.
There is no evidence that sensitive data in the agency's internal computer network had been compromised.
There also were no apparent links to more serious network security breaches recently at the International Monetary Fund and Lockheed Martin Corp. Lulz Security has not been linked to those incidents.
The group announced the attack ;ast night.
"Tango down," the group Tweeted, pointing to cia.gov.
Although the group, also known as Lulz Boat, fashions itself more as pranksters and activists than people with sinister intent, its members have been accused of breaking the law and are wanted by the FBI and other law enforcement agencies.
Lulz broke into a public website of the senate over the weekend and released data stolen from the legislative body's computer servers.
In May, the group posted a false story on the PBS website saying that rapper Tupac Shakur was still alive and living in New Zealand. Shakur was murdered in 1996.