US telecommunications giant T-Mobile is investigating a potential data breach that may have affected 100 million users, after hackers claimed to be selling the data for six Bitcoins ($270,000) on the Dark Web.

The sellers told Motherboard that they have obtained data related to over 100 million people which came from T-Mobile servers and includes Social Security numbers, names, addresses and driver license information

T-Mobile said in a statement on Sunday that "We are aware of claims made in an underground forum and have been actively investigating their validity. We do not have any additional information to share at this time." After reviewing samples of the data, Motherboard reported it appeared authentic.

It’s not clear when the data may have been accessed, but T-Mobile has been the target of several data breaches in the last few years, most recently in December 2020.  During that incident, call-related information and phone numbers for some of its customers may have been exposed, but the company said at the time that it did not include more sensitive info such as names or Social Security numbers.

In 2018, hackers accessed personal information for roughly 2 million T- Mobile customers that included names, addresses, and account numbers, and in 2019, some of T-Mobile’s prepaid customers were affected by a breach that also accessed names, addresses, and account numbers.

A March 2020 breach exposed some T-Mobile customers’ financial information, Social Security numbers, and other account information.

T-Mobile has approximately 100 million customers, which equates to around 200,000 people affected by this breach.