When residents are alerted to a crime involving utility companies, a scammer is often the culprit.

One Arizona utility company is facing an entirely different and far more sophisticated crime, though: a possible data breach that may have stolen information from as many as 30,000 customers.

Goodyear city utility customers were alerted to the possible data breach after a customer reported some fraudulent activity on their accounts. That prompted the city to shut down its online bill payment system until the issue could be investigated and addressed.

Should the evidence show that someone has hacked the online payment portal and used customer information to take over their financial accounts, both the utility service and the other customers owe a debt of gratitude to the victim who took action once the suspicious activity appeared. This kind of diligence is often the only way someone finds out they’ve already been a victim of identity theft or account takeover.

When monitoring your accounts, it’s important to look for a variety of things. It’s not just fraudulent charges, but can be anything like purchases declining, purchases that you don’t remember making, or even tiny “low-dollar” purchases, like a buck or two here and there. Those small purchases may be an indication that someone was “testing” out your account information by making a transaction that is less likely to be caught by fraud detecting software, thereby triggering an alert.

Following news of any data breach—or even a suspected data breach, such as in this case—it’s a good idea to change your passwords on any sensitive or affected accounts. Changing your password frequently means that you’re more likely to be protected if a thief buys a database of old account login information. At the same time, it’s important to secure your accounts with strong, unique passwords in order to prevent software “guessing” of your credentials.

Contact the Identity Theft Resource Center for toll-free, no-cost assistance at (888) 400-5530. For on-the-go assistance, check out the free ID Theft Help App from ITRC.