Dozens of helicopters were being used to fight the Ferguson Fire near Yosemite National Park/Ian Cosenza

Nearly 4,000 firefighters were battling the Ferguson Fire outside of Yosemite National Park on Friday, with efforts being made to keep the flames away from El Portal and Yosemite West with its many vacation homes. Elsewhere in the West, crews were battling fires in Yellowstone, Crater Lake, Sequoia, and Grand Canyon national parks, as well as Whiskeytown National Recreation Area, which was closed due to the Carr Fire.

The tasks at hand were growing increasingly complicated as new and rapidly growing fires were stressing the ranks of firefighters available to combat them.

"With the number of new fires in the Northwest this week, firefighting resources are strained," was the news from Crater Lake National Park, where a nearly 2,500-acre fire was burning in the northeastern section of the park.

The Ferguson Fire, which has forced closure of the Yosemite Valley and Wawona areas of the park due to smoke and firefighting operations on the park roads, the blaze was mapped at nearly 46,000 acres, with attainment along nearly a third of the fire lines.

"Crews along the western perimeter worked on isolated hot spots inside the fire line," said the morning fire report Friday. "To the north, firefighters improved upon existing containment lines, with plans to scout out potential containment lines closer to the fire’s edge during daylight hours. While on the east side, firefighters continued with firing operations to remove available fuels between the fire and the communities of Yosemite West and El Portal. To the south, crews worked in steep terrain to widen and extend constructed containment lines designed to redirect fire that had jumped existing lines two days prior."

Fifty-five helicopters were being used to dump water on the flames, while ground crews were being helped by 93 bulldozers.

At Whiskeytown, the Carr Fire had blown up to nearly 45,000 acres, consumed 65 structures, and led to the evacuation of about 20,000 area residents.

"The fire became very active throughout the evening. Firefighters continue to work aggressively to build containment lines around the Carr Fire. Their efforts have been hampered overnight due to extreme fire behavior and challenging wind conditions," Cal Fire reported Friday morning. "Continued hot dry weather is forecasted for the remainder of the week with triple digit temperatures. The number of damaged and destroyed structures reflected may change throughout the duration of the fire."

Nearly 1,800 firefighters were being supported by 110 fire engines and 10 helicopters.

Blazes in Yellowstone and Grand Canyon were in the backcountry and not posing a threat to structures.

At Grand Canyon, the Obi Fire was burning in the far southwest corner of the Wahalla Plateau above Obi Point. It covered nearly 600 acres Friday morning, The fire was burning through brush and Ponderosa pine forests and crews were working to contain its spread.

The Bacon Rind Fire along the Yellowstone-Gallatin National Forest border in the park's northwestern corner was about 400 acres in size and slowly creeping across a landscape of dead and downed conifers intermixed with live trees. The dangerous nature of the terrain had kept firefighters off the fire lines, though fire bosses were watching to see if the flames moved towards either U.S. 191 or private inholdings in the national forest and had 40 firefighters ready to go.

At Sequoia National Park, the Horse Creek Fire in the John Krebs Wilderness was mapped at 34 acres with containment lines established around 90 percent of the fire. Fire activity has reduced dramatically, with fire mostly smoldering and creeping with a few interior pockets of active flame.