Here's an excerpt from near the end of a USA Today online article that mentions the drones....

"The so-called North Fire began in chaparral just off the interstate, near the junction with
State Route 138. Fanned by 40-45 mph winds. Five drones flying over the area forced fire
officials to temporarily ground air tankers, according to news reports. It was the third time
recently that remote-controlled aircraft had interfered with firefighting in California."