updated as of 9/10 @ 3:31 p.m.
Two Wyoming Army National Guard UH-60 Blackhawk helicopters, equipped with 600-gallon water buckets, were activated to fight the fires on Casper mountain.The helicopters, 11 personnel and support vehicles left Cheyenne this afternoon for Natrona County, after being called to state active duty by Governor Matt Mead.

K2 Radio in Casper is reporting that the fire size estimates are at around 10,000 acres and growing rapidly, according to Casper Fire-ems spokesman Bob Fawcett. He  says all evacuations remain in effect from Bear Trap Meadow east to the Hat Six area. But not including businesses along East 2nd street. The fire jumped East End Road and came over the top of the mountain  and has been burning the north face since mid morning. Fawcett says there is still  fire activity on the south side as well. Multiple structures have been lost, Fawcett says, and assessment of those buildings is in progress. He says additional fire crews continue to arrive.

10 a.m.
The Sheep Herder Hill fire burning in Natrona County has now burned some 5,000 acres.  Natrona County Emergency Management Coordinator Lt. Stu Anderson says no cause is yet known for the fire and the investigation continues. Anderson says according to the air operation folks at least five structures have been destroyed in the blaze.  Anderson says they are very concerned about today's red flag conditions and the chance of thunderstorms. According to the Wyoming State Forestry Division, the fire was reported around 4:30 p.m. Sunday.

Meanwhile The U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA) has authorized the use of federal funds to help with firefighting costs for Wyoming’s Sheep Herder Hill Fire in Natrona County. FEMA Regional Administrator Robin Finegan approved the Fire Management Assistance Grant Sunday night, upon receiving the state’s request.