The number of firefighting personnel is up sharply from the roughly 3,700 who were battling the blaze Tuesday.
The fire, on its way to becoming the sixth-largest wildfire in California history, has already destroyed 111 buildings, including 31 homes, across 281 square miles.
Among the elite hot-shot teams and professional wild-land firefighters are orange-clad convict crews trained by the California Department of Forestry and Fire Protection. The convicts are managed by Cal Fire crew leaders and generally do much of the arduous labor involved in cutting fire lines by hand.
About 34 inmate crews -- or some 500 firefighters -- are on the Rim fire. In addition to wearing their distinctive orange fire gear, inmate crews’ sleeping areas are generally segregated in a fire camp, although they have access to dining tents and other amenities.
Now in its 12th day, the Rim fire has burned an estimated 187,466 acres overall -- including 43,310 acres inside the park's boundaries, in its northwest part of the park, according to U.S. Forest Service officials.
About 4,500 structures remained threatened by advancing fire lines on the eastern and western flanks, according to Cal Fire. And evacuations were ordered for residents in the fire’s path south of California 120 and north of Old Yosemite Road.
Even with the seventh-largest wildfire in California’s history approximately 25 miles away, there was little effect other than traffic obstacles for visitors to the popular Yosemite Valley.
Officials closed a portion of Tioga Road on Wednesday so fire crews could use the east-west route to better access the blaze.