"This was one of the largest data breaches in history," Attorney General William Barr said.
The U.S. has charged four members of China's military in connection with the 2017 Equifax hack.
Attorney General William Barr announced the indictment during a press conference Monday. He said the four hackers got into Equifax's network by exploiting a security issue in the company's dispute resolution webpage.
Barr said once they were inside the network, they "spent weeks conducting reconnaissance, uploading malicious software and stealing login credentials."
The indictment alleges the hackers obtained the names, birth dates and Social Security numbers of nearly 150 million Americans, as well as at least 10 million driver's license numbers. They're also accused of stealing company trade secrets.
Last year, Equifax agreed to pay up to $700 million to settle the data breach. The bulk of that money was intended for customers affected by the hack.