Most days, U.S. Customs and Border Protection Officer David Gasho sends three unmanned spy planes into the skies over the rugged Sonora Desert to hunt for drug smugglers crossing into southern Arizona from Mexico.

But in mid-June, as the largest wildfire in Arizona history raged, Gasho sent one of the Predator B drones soaring over residential neighborhoods in search of another threat -- rogue brush fires. Working from an air-conditioned trailer, his crew aimed an airborne infrared camera through thick smoke and spotted a smoldering blaze.

Using coordinates fed from the drone, airborne firefighters then doused the hot spot from helicopters and watched over a secure Internet feed as the heat signature of the flames cooled.

It was the latest example of once-secret military hardware finding routine civilian uses. Seven surveillance drones are chiefly used to help patrol America's northern and southern borders. But in recent months, they also have helped state and local authorities fight deadly fires, survey damage from floods and tornadoes, and inspect dams and levees.