FRESNO, Calif. — After burning for nearly a week on the edges of California’s Yosemite National Park, a massive wildfire of nearly 200 square miles has now crossed into it, and firefighters have barely begun to contain it.

The Yosemite Valley, the part of the park frequented by tourists and known around the world for such iconic sights as the Half Dome and El Capitan rock formations and Yosemite falls, remained open, clear of smoke and free from other signs of the fire that remained about 20 miles away.

But the blaze was reverberating around the region. It brought a governor’s declaration of emergency late Friday for San Francisco 150 miles away because of the threat the fire posed to utility transmission to the city, and caused smoke warnings and event cancellations in Nevada as smoke blew over the Sierra Nevada and across state lines.

And the fire had established at least a foothold in Yosemite, with at least 17 of its 196 square miles burning inside the park’s broad borders, in a remote area near Lake Eleanor where backpackers seek summer solace.

Park spokeswoman Kari Cobb said that the park had stopped issuing backcountry permits and had warned those who already had them to stay out of the area.

But she emphasized, “Right now there are no closures, and no visitor services are being affected in the park. We just have to take one day at a time.”