When Mike Cypert got the call that utilities in remote Texas communities were being hacked, he raced across his office to unplug the computer that ran his city’s water system.

Hale Center is a dusty, cotton-growing burg of 2,000 about five hours drive northwest of Dallas. After the alert from a software vendor in January, Cypert, the city manager, said he found thousands of attempts to breach Hale Center’s firewall, some coming from an Internet address that traced back to St. Petersburg, Russia.