Smoke from the Dixie Fire could be seen Wednesday from the park's Kohm Yah-mah-nee Visitor Center/NPS

Editor's note: This updates with the fire being inside park boundaries, efforts to make sure all visitors are out of the park, provides additional details.

As the northern edge of California's massive Dixie Fire burned into Lassen Volcanic National Park on Thursday, rangers were sweeping the park's trails to ensure any remaining visitors were told to leave the park, which had closed because of the flames.

"We're currently evacuating campgrounds and trails. We have rangers on the trails now making sure that we're doing a clean sweep," Ranger Kevin Sweeney said during a phone call. "We want to be ready for when that firefighting needs to happen in the park and not have any kind of intrusions for them. The fire's currently on the east side of the park. It's in the Warner Valley and Juniper Lake areas."

Extreme fire conditions -- high ambient air temperatures, low humidity, and gusting winds -- had pushed the fire roughly 50,000 acres overnight, blowing it up to more than 322,500 acres. Those conditions had firefighters dealing with long-range spotting of sparks ahead of the main fire, crown fires that turned trees into oversized torches, and the possibility of "group torching" of multiple trees at once.

The Dixie Fire had moved into the southeastern corner of Lassen Volcanic National Park.

The unpredictable nature of the fire late last month prompted a ban on backcountry camping in Lassen, and the Warner Valley and Juniper Lake areas were closed to all visitors because there was only one-way in, and one-way out. At that time the fire was about a dozen miles southeast of the national park.

"We've been prepping structures in Warner Valley and at the Juniper Lake area for the past couple of weeks," Sweeney said as a retardant plane flew overhead. "And we've been in close communication with several inholders in Juniper Lake. We gave them warning about two weeks ago. And then when we did the closure on July 24, we made sure that all those in-holders were out of the park."

Among the inholders who headed out were the operators of the popular Drakesbad Guest Ranch.

As for checking the park's trails for any hikers or backpackers, the ranger said "we can never be absolutely sure that everybody's out. But we are pretty confident that we'll be able to get contact with everyone."

"Lassen, as you know, is not a huge swath of land," he continued. "So we should be able to hit those areas where we think folks might be pretty quickly. The other thing that we have going for us is that the surrounding area has been so heavily impacted by smoke that our visitation has been really low for the past few days, actually the past couple of weeks. And in addition to that, the evacuation orders that went out over the past several days have really lessened traffic."