SAN FRANCISCO — A firefighter from Texas killed battling a wildfire in the Northern California forest was working the fire lines when her truck rolled off a remote backcountry road as she tried to escape the flames, fire officials said.

Diana Jones, 63, was an emergency medical technician with the Cresson Volunteer Fire Department in Texas who had spent the last few summers doing contract firefighting with her son, a captain with the department, the fire department said in a statement published Wednesday on its Facebook page.

“We’re all numb. We’re shell-shocked. She’ll be sorely missed,” Cresson Fire Chief Ron Becker told KQED News.

A retired hairdresser, Jones had been a volunteer firefighter and emergency medical technician in Cresson, a community of 1,000 people about 25 miles south of Fort Worth, for nearly five years. She and her son, Captain Ian Shelly, would travel to the Pacific Northwest to work on wildfires, Becker said.

Jones was working at a blaze Monday in Tehama County when the fire became more active. She and another firefighter got into their truck to escape the flames. As they reversed the vehicle, it plunged about 15 feet down an embankment and slammed into a tree, CHP spokesman Omar Valdez told KQED News.

Jones was not able to escape the vehicle as fire engulfed it, Valdez said. The other person in the vehicle was able to get out but suffered burns that required hospitalization.

Jones’ Death Marks the Second Fatality Among First Responders Helping Battle Wildfires

The complex burning in timber, chaparral and tall grass began as 37 separate fires but many have either been contained or merged, according to the Forest Service.

Jones’ death marks the second fatality among first responders helping battle wildfires in California since mid-August when thousands of lightning strikes ignited hundreds of blazes around the state.

Many blazes continued to burn Wednesday and firefighters working to contain them were cautioned about increasingly warm and dry conditions heading toward the Labor Day weekend.

The two largest fires, east and north of San Francisco Bay, were each at least 70% surrounded, the California Department of Forestry and Fire Protection said Wednesday. A third big fire, burning to the south in the Santa Cruz Mountains region, was 46% surrounded.

The progress has allowed thousands of people to return home but nearly 40,000 remained under evacuation orders, Cal Fire said.

The fires have destroyed more than 5,800 structures destroyed, many of them homes and killed eight people.

Hundreds of wildfires ignited after a massive electrical storm unleashed thousands of lightning bolts have burned more than 2,218 square miles.