SAN FRANCISCO – Steep terrain and roadless forest land are hindering the push to get the last of California's wildfires under control.

Thick smoke from the fire burning in the Shasta-Trinity National Forest near Junction City has grounded firefighting helicopters and air tankers. A mandatory evacuation order remained in effect Wednesday for the outlying neighborhoods of the Trinity County town of about 800 residents.

That fire has thus far burned 98 square miles and was about 61 percent contained.

As wildfires elsewhere in the state near complete containment, firefighting resources were being redirected to more rural areas, said Frank Mosbacher, spokesman for the U.S. Forest Service. The includes more than 250 National Guard troops assigned to the fire near Junction City.

“Topography and resources are the big challenge,” Mosbacher said.

More then 2,000 blazes have blackened 1,528 square miles of land across California over the past month. On Wednesday, 33 blazes were still active.