data breach could affect every federal agency chinese hackers federal government notify millions employees work assess impact massive data breach involve agency handle security clearances employee records.a foreign entity government believe behind cyber attack u.s. officials investigate whether chinese hackers involve reuters report cite source familiar matter fbi work interagency partner investigate matter take potential threats public private sector systems seriously continue investigate hold accountable pose threat cyberspace fbi spokesman tell cnbc.a congressional aide familiar situation decline name authorize discuss say office personnel management interior department hack second u.s. official also decline identify say data breach could potentially affect every federal agency.the opm plan notify approximately million individuals whose personally identifiable information pii may compromise breach agency say release since investigation on-going additional pii exposures may come light case opm conduct additional notifications necessary release said.read cnbc break massive cyber attack federal employee info