The FBI and CISA previously said they were investigating breaches by a China-backed hacking group inside several telecommunications providers, but had not said whether any data was stolen or whether the hackers accessed the systems used to fulfill legal wiretap requests.

The U.S. has indicted two individuals, Connor Moucka and John Binns, according to new documents, for hacking third-party cloud data storage and analytics company Snowflake. The Snowflake hack led to data breaches at numerous companies using the platform such as AT&T, Ticketmaster, and more than 150 other corporations.

Prosecutors identified two hackers behind a massive AT&T data breach. Several other Snowflake customers experienced similar breaches.

The U.S. government has accused Connor Moucka and John Binns of being the hackers who broke into the systems of AT&T, stealing around 50 billion customer call and text records. In July, AT&T said hackers stole the phone records of “nearly all” of its cellular and landline customers,