target of a high-tech invasion. chinese hackers broke into a u.s. government computer system and stole personal information on at least four million current and former federal employees. chief white house correspondent major garrett is following this developing story. >> reporter: federal cyber officials first noticed the hack of government servers in april. in early may, investigators confirmed hackers infiltrated the office of personnel management. the clearing house for all federal employee records, and the interior department. the four million current and former federal employees are at risk because the hack reached into databases containing what the government calls personally identifiable information including job assignments, performance ratings, and training. officials said the hack did not access information collected in background or security clearance investigations. they warned the investigation could reveal more federal employees at risk. the process of notifying those affected will begin next week.