A sign for a T-Mobile store is seen in Manhattan, New York, U.S., April 30, 2018. REUTERS/Shannon Stapleton - RC18461BBA10

(Reuters) - T-Mobile US Inc TMUS.O and its unit Metro PCS informed customers on Thursday about a potential security breach that was discovered and shut down by the company.

The cyber-security team found and shut down unauthorized access to certain information on Aug. 20, and reported the matter to authorities, T-Mobile said in a statement t-mo.co/2wrr9Cq on its website.

No financial data, social security numbers or passwords were compromised, but other personal information like name, email-id, phone number, zip code, account number or type (postpaid or prepaid) may have been exposed, the company said.

About 3 percent of T-mobile's 77 million customers could have been affected, a company spokesperson told bit.ly/2wknfLr technology news website Motherboard.

T-Mobile did not respond to Reuters request for comment outside regular business hours.