TOQUERVILLE, Washington County — A human-caused brush fire east of I-15 has grown to 100 acres and is threatening mobile homes.

The Toquerville Falls fire started Saturday morning, said Nick Howell, fire management specialist with Cedar City Bureau of Land Management. Firefighters found a point of origin for the blaze, but they aren't saying exactly how it started.

Residents are evacuating their mobile homes, Howell said, though the fire's threat isn't imminent.

Crews are burning a ring around the fire and hope to contain it by Saturday night. A handful of fire engines, aircraft and a water tender are battling the blaze. Firefighters may get some help from a storm forecast to drench the area this weekend.

All of Washington County and much of southeastern Utah is under a flash-flood watch due to thunderstorms moving in from Arizona, according to the National Weather Service in Salt Lake City. The watch is in effect through Sunday evening.