(NEXSTAR) – Thousands of Fidelity Investments customers may have had their personal information stolen amid a data breach that occurred in August of this year, according to the financial firm.

The breach took place between August 17–19, with Fidelity becoming aware of the activity on Aug. 19, according to a spokesperson for the company. Fidelity stopped access to the “third party” who had breached the accounts on the 19th, and subsequently launched an investigation “with assistance from external security experts,” the spokesperson said.

Fidelity has said the hackers did not gain access to any of its customers’ funds or accounts, but did not disclose which specific information was obtained during the breach.

A total of 77,099 Fidelity customers were affected by the security incident, an attorney for Fidelity told the Office of the Maine Attorney General.

Fidelity intends to begin notifying the affected customers by mail, according to the Maine Attorney General’s office.

A spokesperson for Fidelity, in a statement obtained by Nexstar, said customers whose accounts were compromised will be offered free credit monitoring. A sample letter shared with the Maine AG’s office indicated that customers will be offered 2 years’ worth of the services.

Fidelity’s letter adds that customers should “remain vigilant for fraudulent activity or identity theft” by keeping close tabs on their accounts and reporting suspicious activity in a timely manner.

Customers can also call Fidelity with questions at 1-844-528-1265, Monday through Friday, according to the letter.

“We recognize our customers may have questions about this event and we have resources in place to assist them,” a Fidelity spokesperson said in the statement shared with Nexstar. “Fidelity takes its responsibility to serve customers and safeguard information seriously.”