Federal websites back online after Anonymous attack

Anonymous claims it was responsible for taking down Justice, FBI and music company websites in wake of Megaupload crackdown.
(CNN) -- Most of the websites shut down by a hackers group were up and running early Friday, including the U.S. Department of Justice, FBI and some entertainment sites after one of the federal government's largest anti-piracy crackdowns.

"Hacktivist" collective Anonymous took credit for taking down the sites Thursday after the arrests of leaders of Megaupload.com and shut down the popular hub for illegal media downloads.

Hours after the announcement of the arrests, some of Megaupload's fans turned the table on the feds, knocking the U.S. Department of Justice and the FBI websites offline.