The city of Tyler said Monday that an unknown third party hacked into a payment system that residents use to pay their water bills and municipal court fees.

Spokeswoman Julie Goodgame said the city found out about the breach when the U.S. Secret Service contacted the city. The issue is now being investigated at the federal level, she said.

The city sent out a news release late Monday morning describing the problem, saying the city took action to shut down the service and relaunched it with additional security, and encouraged users to monitor their credit.

The Secret Service contacted the city on Aug. 27 and the system was brought down the same day, secured and brought back online Aug. 31, Goodgame said.

The hackers attacked the Click2Gov online payment system, potentially affecting customers who made payments online or in person, but not affecting payments made through the 24-hour kiosk or over the phone, according to the news release.

“We apologize for and deeply regret any inconvenience or concern this may cause,” the news release said. “We are taking all necessary steps to investigate the breach and ensure the most secure online experience possible for our customers.”

The city said the breach took place sometime between June 18 and Aug. 21. The information affected includes people’s credit card numbers, security codes and expiration dates, as well as their first and last names, middle initials and addresses.

“Upon notification, we immediately shut down our payment connection to Superion, the Click2Gov software provider, and began working with them to determine if our customers’ information was compromised,” the news release said.

“We then implemented additional security measures designed to prevent a recurrence of such an attack, and to protect your privacy. The online payment system has been secured and is back online. We are working closely with law enforcement to ensure the incident is properly addressed.”

Goodgame said the city also has been contacting customers individually to alert them of the issue. She said the city plans to translate information on the breach to reach affected Spanish-speaking residents.

Bill Mack, the resident agent in charge of the Secret Service’s Tyler office, said the agency generally performs investigations of financial crimes but does not comment on ongoing criminal investigations.

“One of the best things to do for any people who may be concerned about their credit card being breached is to review their credit card statement, and if they see any unauthorized charges on them to call their bank,” Mack said.