Fire erupted on Cow Mountain, east of Ukiah early Monday afternoon, reaching ten acres and further taxing already strained firefighters battling a 900-acre fire to the north, in Redwood Valley.

Reports of a fire near the public rifle range on Cow Mountain, managed by the Bureau of Land Management, began coming in just after noon, Ukiah-area fire officials said.

From Ukiah, a cloud of white smoke could be seen rising from the top of the mountain range.

CalFire officials said they were rerouting firefighters from the Grade fire in Redwood Valley, where fire broke out Sunday afternoon, to Cow Mountain. The size of the fire was not available, but it was reported as having the potential to reach 1,000 acres, area fire officials said.

The Grade fire was last reported late Monday morning as being 25 percent contained.