Equifax Inc. CEO said the recent security breach, which impacted up to 143 million Americans, was the "most humbling moment in our 118-year history" and promised changes to better protect customers.

"Our top priority is doing everything we can to support affected consumers," Richard Smith said in an op-ed published Tuesday. "Our team is focused on this effort, and we are engaged around the clock in responding to millions of inquiries from consumers. Importantly, outside investigators found no evidence of unauthorized activity on our core consumer or commercial credit reporting databases."

"We are devoting extraordinary resources to make sure this kind of incident doesn't happen again," he added. "We will make changes and continue to strengthen our defenses against cyber crimes. We will make sure every consumer who wants protection has a full package of services. And we will continue to update everyone on our progress."

The credit monitoring agency disclosed Thursday that "criminals" violated a U.S. website application vulnerability to gain access to certain files between May and July. Equifax said became aware of the breach on July 29.

Information collected primarily includes names, Social Security numbers, birthdays, addresses, and even driver's license numbers. Approximately 209,000 American consumers had their credit card numbers collected and dispute documents with personal information for approximately 182,000 Americans was retrieved.

The FBI is investigating the security breach, according to ABC News. Likewise, an independent cybersecurity firm has been hired to provide recommendations to prevent another cybersecurity incident from occurring.

The Senate Finance Committee submitted a letter Monday to Smith and requested answers to 13 questions, including a detailed timeline of the breach and its discovery, the company's plan to notify affected consumers, what steps the company has taken to limit potential consumer harm related to the breach, among other inquiries.

Equifax has until Sept. 28 to respond to the Senate Finance Committee.