F.B.I. Investigates Leak of iPad E-Mail Addresses

The group also obtained the identification numbers known as ICC-IDs that those iPads use to communicate over AT&T's network.

“The F.B.I. is aware of these possible computer intrusions and has opened an investigation to address the potential cyberthreat," said Jason Pack, a supervisory special agent with the F.B.I.'s news media office.

The iPad owners who were affected included some prominent corporate executives and senior officials from several government agencies including the Justice Department, the Department of Homeland Security and the White House.

AT&T said it was made aware of the breach on Monday and closed the security loophole as of Tuesday afternoon. Although the company said it was still looking into the matter, it said it did not believe “that any other customer information was shared."