US money transfer giant MoneyGram has confirmed that hackers stole its customers' personal and transaction details in a cyberattack last month.

The company said in a statement Monday that an unauthorized third party “accessed and obtained customer data” during the Sept. 20 cyberattack. The cyberattack – the nature of which is still unknown – triggered a week-long outage that brought the company's website and app offline.

MoneyGram says it serves over 50 million people in more than 200 countries and territories each year.

In its statement Monday, MoneyGram said the investigation was still in the “early stages” and was working to determine which consumers were affected by this issue. The company did not say how many customers might be affected. When reached, MoneyGram spokesman Sydney Schoolfield had no comment beyond the company's statement.

Stolen customer information includes names, phone numbers, mailing and email addresses, dates of birth, and national identification numbers. The data also includes a “limited number” of Social Security numbers and government identification documents such as driver's licenses and other documents that contain personal information such as. B. Utility bills and bank account numbers. MoneyGram said the type of data stolen will vary from person to person.

MoneyGram said the stolen data also included transaction information, such as dates and amounts of transactions, and “for a limited number of consumers, criminal investigation information (e.g., fraud).”

TechCrunch previously reported that MoneyGram subsequently notified U.K. data protection authorities of a data breach, as required by U.K. law.

Updated with response from MoneyGram.