Members of China-based hacking group were indicted for series of computer intrusions, including the 2015 Anthem data breach that affected over 78 million people.

The four-count indictment alleges that Fujie Wang, 32, and other members of the hacking group, including another individual charged as John Doe, conducted a campaign of intrusions into U.S.-based computer systems of large businesses, according to a May 9 DOJ press release.

Authorities allege the defendants gained unauthorized access to the computer systems of Anthem and three other U.S.-based firms beginning in Feb. 2014, using sophisticated techniques to ultimately install malware to further compromise the systems and obtain sensitive data.

“The allegations in the indictment unsealed today outline the activities of a brazen China-based computer hacking group that committed one of the worst data breaches in history,” Assistant Attorney General Benczkowski said in the release. “These defendants allegedly attacked U.S. businesses operating in four distinct industry sectors, and violated the privacy of over 78 million people by stealing their PII.”

The defendants allegedly then transferred the data in Anthem’s enterprise data warehouse from the United States to China.