Yosemite: Hwy 120 Closed East of Groveland

The Rim fire has transitioned into unified command with Cal Fire and Forest Service on August 21 at 2:00 p.m.
Fire continues its eastward spread along Packerd Canyon Road and Pilot Ridge. Structure defense continues for San Jose Camp, Spinning Wheel and Tawonga Camp as the fire moves up the middle fork of the Tuolumne.
The fire continues to spread northwest burning past Butcher Knife Ridge and moving into Grapevine Creek; northeast up the Tuolumne River Drainage from the Gravel Range past Jones Point Lookout; and continue to spread southeast edge along Hwy 120 to the east.
Firing operations have begun on Ferretti Rd. as the fire progress west towards the community of Pine Mountain Lake. Direct suppression methods have been successful.
The availability of fixed wing air craft is pertinent to the success of suppression operations. The use of Maffs C-130s and the V-LAT DC-10 has greatly improved suppression efforts. Use of Military Rotary wing aircraft continues today.
In the next 24 hours the fire is expected to continue up the Tuolumne River canyon, and continue its spread to the north and east.
Due to inaccessible, steep terrain and active fire behavior a combination of direct and indirect attack will be used on this incident. Direct line suppression efforts are impeded by difficult access and steep inaccessible terrain. Active fire behavior today raises safety concerns for crews adjacent to the fire’s edge. Smoke exposure within the deep drainage of the Clavey River will be an issue for fire crews as well.

Any word on how this started? Inciweb just says "under investigation"...you guys hear anything else?