U.S. law enforcement officials

U.S. law enforcement officials also told FoxNews.com that the arrest of a 16-year-old hacker in London, who goes by the online user name Tflow, was related to the raids in the U.S.

Some of the arrests were out of the San Francisco field office, sources said. Earlier in the day, the FBI executed search warrants at the New York homes -- two in Long Island, N.Y., and one in Brooklyn, N.Y. -- of three suspected members of Anonymous, FoxNews.com reported.

More than 10 FBI agents arrived at the Baldwin, N.Y., home of Giordani Jordan with a search warrant for computers and computer-related accessories, removing at least one laptop from the premises.

The Anonymous group is a loose collection of cybersavvy activists inspired by WikiLeaks and its flamboyant head Julian Assange to fight for "Internet freedom" -- along the way defacing websites, shutting down servers, and scrawling messages across screens web-wide.

The Anonymous vigilante group recently turned its efforts to the Arizona police department, posting personal information of law officers and hacking and defacing websites in response, the group claims, to the state's controversial SB1070 immigration law.

While Anonymous is largely a politically motivated organization, splinter group LulzSec -- which dominated headlines in the spring for a similar streak of cyberattacks -- was largely in it for the thrills.

The metropolitan police in London arrested the first alleged member of the LulzSec group on June 20, a 19-year-old teen named Ryan Cleary. Subsequent sweeps through Italy and Switzerland in early July led to the arrests of 15 more people -- all between the ages of 15 and 28 years old.

The two groups are responsible for a broad spate of digital break-ins targeting governments and large corporations, including Japanese technology giant Sony, the U.S. Senate, telecommunications giant AT&T, Fox.com, and other government and private entities.