U.K. police have arrested five men in connection with an online collective known as "Anonymous," which authorities and computer specialists say are behind recent attacks on companies and organizations that had tangled with document leaking Web site WikiLeaks. London's Metropolitan Police Service said that it had arrested the men, who are between 15 and 26 years old, in dawn raids Thursday at their homes. The arrests relate "to recent and ongoing 'distributed denial of service' attacks (DDoS) by an online group calling themselves 'Anonymous,'" the police said.