ARDMORE, OK -- Quick thinking by city officials in Ardmore may have kept hundreds of Texoma-area bank accounts from being hacked.

Information technology specialists with the city told KTEN that a hacker targeted more than 20,000 people across the U.S. Some 600 of that number pay their bills through the city and had their accounts tampered with.

Officials said hackers attempted to target those who have their water bills automatically withdrawn from their bank accounts. Digital intruders may have tried to copy information from a water bill that was sent out back in April.

"All of a sudden, something that looked very similar to that bill showed up again," said Robert Newell, Ardmore's information technology director. "It had the same account numbers, it was off by a little bit, but it became pretty evident that, that data is very similar to the one that went out April 25."

The city voted to open two new bank accounts with heightened levels of security to make sure no funds would be lost.

Until then, third-party professionals were hired to help find out how hackers broke the system.

Newell said it is already clear that these alleged hackers knew what they were doing.

"It wasn't just someone with spare time at home," he said. "This was probably a very advanced group that figured out how to do this."

Contact your financial institution if you think your account information may have been placed at risk.