An estimated 143 million U.S. consumers could be affected by a cyber security attack carried out by suspected criminal hackers, national credit-reporting company Equifax said Thursday.

The unauthorized access occurred from mid-May through July 2017 primarily involved names, Social Security numbers, birth dates, addresses and, in some cases, driver's license numbers, the company said in a detailed announcement of the embarrassing attack.

Additionally, the hackers gained access to credit card number for roughly 209,000 consumers, plus certain dispute document with personal identifying information for approximately 182,000 consumers.

Equifax also identified unauthorized access to limited personal information for certain United Kingdom and Canadian residents.

However, there was no evidence of unauthorized activity on Equifax's core consumer or commercial credit reporting databases, the company said.

"This is clearly a disappointing event for our company, and one that strikes at the heart of who we are and what we do. I apologize to consumers and our business customers for the concern and frustration this causes," Equifax Chairman and CEO Richard Smith said in a statement issued with the announcement.

The news sent shares of Equifax (EFX) down 5.4% to $135 in extended Thursday trading.

To find out if you are affected by the breach, you can check here.