Sensitive security files for 22.1 million people were obtained during two big security data breaches last year that have been blamed, in private, on the Chinese government. That number is much bigger than what was originally disclosed, and includes not only federal employees but also the friends and family of federal employees listed as references.

U.S. officials told reporters on Thursday about the scope of the breaches, which many say amounts to the largest and most affecting cyber-security hack in U.S. government history. The hacked files contain a range of information, including social security numbers and information related to job interviews and assignments, according to the Washington Post.

“It is a very big deal from a national security perspective and from a counterintelligence perspective,” said FBI Director James B. Comey on Thursday. “It’s a treasure trove of information about everybody who has worked for, tried to work for, or works for the United States government.”

The figure cited on Thursday is much higher than any other estimate previously given. In addition to some of the more obvious dangers for the victims whose information has been stolen, the hackers could potentially identify undercover agents living abroad by cross referencing the data with embassy data abroad.

The hacks are one of several high profile data breaches in the U.S. government recently.

In May, the officials admitted that the Internal Revenue Service had been hacked by criminals who then took information on 100,000 tax accounts. That breach began in February, and allowed the hackers to get social security information, dates of birth and addresses.

In April, it was announced that Russian hackers had gotten into the White House data networks and accessed the president’s schedule, and that the unclassified Defense department data networks had also been hacked.