Authorities ordered another evacuation Wednesday at a popular reservoir along the California-Nevada line where a pair of wildfires continue to grow north of Reno.

Nearly 300 firefighters on the lines turned back immediate threats to homes or other structures, and more crews were on their way to the Plumas National Forest’s Beckwourth Complex Fire on the Sierra’s eastern front, fire officials said.

The fires sparked by lightning last week have burned more than 4 square miles of timber, grass and brush about 45 miles northwest of Reno.

More than two-thirds of the burned area is at the Sugar Fire, which jumped containment lines and more than tripled in size Tuesday in winds gusting to 20 to 35 mph, said Jake Cagle, fire operations manager for the Plumas National Forest.

It was estimated to be 34% contained on Wednesday. No injuries have been reported at either blaze.

Crews spent the night protecting homes around the clock after evacuations were ordered Tuesday in the Dixie Valley and Maddalena. The evacuation was extended Wednesday to include all campgrounds and residences around Frenchman Lake northeast of Beckwourth. An evacuation center was set up at a church in nearby Portola.

Crews were having to contend with especially rough terrain in addition to extremely dry conditions, Cagle said.

“It’s really rocky, steep country,” Cagle said during a Wednesday morning briefing posted on the forest’s Facebook site.

“We have a lot of crews and engines and aircraft coming in to hit this thing hard today,” he said. “We’re taking advantage of no wind right now. But we do expect some more growth today as those winds come in.”

Crews were being moved to the Sugar Fire from the Dotta Fire, which has burned about one square mile further north and was 40% contained.