The FBI raided several New York area homes Tuesday during a probe into the hacker group Anonymous.
The amorphous, loosely organized group of hackers sympathetic to WikiLeaks has claimed responsibility for numerous attacks against corporate and government websites around the world.
FBI spokesman Jim Margolin said agents searched residences and seized computers at one address in Brooklyn and three on Long Island. He declined further comment.
The targets of the searches were not named.
Anonymous, known for attacks on the Church of Scientology and Kiss bassist Gene Simmons, claimed credit for disrupting the websites of Visa and Mastercard in December when the credit card companies stopped processing donations to WikiLeaks and its founder Julian Assange.