A server at the U.S. Federal Aviation Administration was illegally accessed online and personal identity information of employees was stolen, the agency said.
Two of the nearly 50 files on the breached computer had personal data about more than 45,000 FAA employees and retirees who were on the FAA rolls as of three years ago, the FAA said in a statement released on Monday.
The server that was breached was not connected to the air traffic control system or other operational systems, according to the statement.
The agency is notifying all affected employees by mail and is investigating the data theft.
The statement did not say when the breach occurred or when the FAA learned of it. An FAA representative did not immediately return a call seeking comment on Tuesday.