First reported at 3:56 p.m., the Detwiler fire was reported burning near Detwiler Road and Hunters Valley Road, 2 miles east of Lake McClure. Within three hours, it had grown to over 1,000 acres as it spread primarily to the northeast. Mandatory evacuations were ordered for all homes along Detwiler Road, Hunters Valley Road, and Hunters Valley Access Road. A Red Cross Evacuation Shelter was set up at McCay Hall, in Catheys Valley. By nightfall, the fire was 2,500 acres in size with zero percent containment.

On the morning of Monday, July 17, the fire was a reported 7,100 acres (2,900 ha) with still zero percent containment as intense heat, windy conditions and limited resources hampered suppression efforts.  Severe fire actively further lead to the evacuation of the Bear Valley area, south of the fire. Highway 49 was also closed due to the fire.

A state of emergency was declared on Tuesday, July 18, 2017 as the fire exploded to over 25,000 acres within the day. The entire community of Mariposa was put under a mandatory evacuation order as over 5,000 structures were threatened. Yosemite National Park remained open, however, some access roads were closed and the fire caused smoky conditions throughout the park.

By the morning of Friday, July 21st, the fire has been reported at 74,083 acres at 15% containment. 118 structures are reported as destroyed, with 58 of those being homes (Wikipedia)