SHASTA-TRINITY NATIONAL FOREST, Calif. >> California is taking a financial wallop from unrelenting wildfires that have drained its firefighting budget and prompted nearly $1 billion in property claims even before the start of the dangerous fall fire season, officials said today.

The disclosures came as a roaring blaze in a rural area near the Oregon border closed 45 miles (72 kilometers) of heavily traveled Interstate 5, the main highway from Mexico to Canada.

Fierce orange flames forced panicked truckers to abandon big-rigs and brought screams from motorists as they watched the advancing fire in Shasta-Trinity National Forest.

A decision was expected Friday on when to reopen the highway.

The wildfire flared just weeks after a blaze in the Redding area killed eight people and burned about 1,100 homes.

California’s insurance commissioner said today that victims of that fire and one in the Mendocino area — the two largest blazes in the state so far this year — have filed more than 10,000 claims so far totaling $845 million.

The two wildfires destroyed or damaged a combined 8,800 homes and 329 businesses.

“The worst may be yet to come,” Commissioner David Jones warned at a San Francisco news conference, noting that California wildfires are typically more destructive after Sept. 1.

Last year, for example, wildfires that killed more than 40 people and destroyed thousands of buildings in counties north of San Francisco didn’t spark until October.

Also today, the director of the state’s firefighting agency said in a letter to lawmakers that the agency only had about $11 million remaining in its annual budget and anticipates needing another $234 million to add firefighters and helicopters, and to cover other costs of fires expected later this year.

The department had spent $432 million through the end of August, said Ken Pimlott of the California Department of Forestry and Fire Protection.

The Legislature budgets for firefighting costs based on historical averages. Cal Fire has requested extra money in seven of the past 10 years but never this early, according to the Department of Finance.

In far Northern California, officials said they had no plans to re-open Interstate 5 today and would reevaluate early Friday — a decision that slowed or stalled truckers who rely heavily on the highway to transport goods along the West Coast.

They were advised to take an alternate route adding 100 miles (160 kilometers) that could take at least six hours.

“If you don’t need to make the trip, I wouldn’t do it,” Caltrans spokeswoman Denise Yergenson said.

Truck driver Amit Sekhri said he saw flames and slowing vehicles along the freeway on Wednesday but his big-rig was too large to turn around and he decided against parking and fleeing on foot.

He kept driving, with fire lapping at both sides of the highway and burning ash falling all around him. He felt the heat in his cab, despite the air conditioning.

“It was picking up so fast. It was behind me, in front of me, left, right. It was all fire. I was surrounded by fire,” he said, still shaken by the experience.

When he finally saw daylight, he knew he had made it to safety.

“It’s one of the scariest things I’ve ever seen and been through,” he said.

The fire began Wednesday and nearly tripled in size overnight, officials said, to 23 square miles (60 square kilometers). It prompted mandatory evacuations and was moving rapidly but remained far from any large towns.

David Steinberg and his partner Kim Mears were returning from a day hike when they came upon the wildfire and watched in awe.

Steinberg says they were mesmerized by the fire, but eventually realized the danger it presented.

“There’s a moment when you’re saying, ‘This is really exciting.’ Then you realize, ‘Oh this could be really dangerous,’” he said.

Elsewhere in the state, a fire burning in the Sierra Nevada had grown to more than 7 square miles (18 square kilometers) after shutting down stretches of U.S. 395, State Route 108 and the Pacific Crest Trail along the eastern spine of California.

The Marine Corps Mountain Warfare Training Center, campgrounds and other areas were evacuated Wednesday. Ranchers were told to prepare to move livestock out of the area in Humboldt-Toiyabe National Forest.