According to U.S. government officials, Chinese hackers broke into the computer networks of the Office of Personnel Management, which houses the personal information of all federal employees. The hackers were targeting information on the thousands of employees who have gone for top-secret security clearances, and had gained access to some of the databases before authorities found the breach and blocked them. It is not yet known how they hacked the network. According to the Department of Homeland Security, they have not “identified any loss of personally identifiable information.” It is also not clear if the hackers were part of the Chinese government. The last known successful hacking of the U.S. government took place last year, when hackers made off with data from the Department of Energy.