At least one person has died in a wildfire near Sacramento that was started this week by a man operating equipment whose sparks flew into dry vegetation, the authorities said on Thursday.

The man, Herbert Wayne Smith of Valley Springs, Calif., was arrested on Wednesday and charged with recklessly causing a fire after he used the equipment without proper precautions in a rural area about 60 miles southeast of the state capital, the authorities said. He was also charged with allowing the fire to spread out of control.

The Calaveras County Sheriff’s Office said on Thursday that it had found a body inside a burned home in a rural area about four miles east of where the fire started. The person’s identity has not been confirmed and will be withheld until the person’s family is notified, the sheriff’s office said in a statement.

Efforts to reach Mr. Smith on Thursday were not immediately successful, and it was unclear if he had a lawyer.

In an interview published on Wednesday by the TV news outlet KCRA, Mr. Smith, 65, said he had been using a small power saw to cut scrap metal on Monday when the fire ignited.

He had been cutting the metal, he told the news outlet, to try to make money for a birthday dinner with his wife. He told KCRA he was “so sorry for everything that’s happened” and said the fire was an accident.

“I turned around, and all of a sudden I just I noticed fire was behind me,” Mr. Smith told the news outlet. “If I could, if I could go back in time and change it, I would,” he added. “But I can’t go back in time.”

As of Thursday afternoon, the blaze, known as the Gann fire, was 26 percent contained and had burned more than 10,000 acres. The fire also has injured a firefighter and destroyed at least seven structures, according to the California Department of Forestry and Fire Protection, the state’s firefighting agency. More than 1,400 people have been evacuated from their homes and another 1,400 remain under evacuation warnings.

Gov. Gavin Newsom of California declared a state of emergency on Thursday, authorizing state agencies to support local response efforts. The Federal Emergency Management Agency has also authorized the use of federal funds to assist in fighting the blaze.

The Gann fire ignited amid a spell of unusually warm and dry weather, quickly spreading through brush and timber in the foothills of the Sierra Nevada.

“The vegetation is pretty crispy right now,” said Brent Wachter, a fire meteorologist with the U.S. Forest Service in Redding, Calif.

Even hotter weather, with temperatures of up to 103 degrees, was expected in Calaveras County over the weekend as a heat wave builds across the Western United States.

Mr. Wachter said winds had been relatively calm this week but could pick up slightly in the coming days and make firefighting more challenging.

Wildfire season runs year-round in California, and this year has been unusually quiet so far. Cool air coming off the Pacific Ocean has helped prevent heightened wildfire activity this summer.

“We’ve had that air-conditioning effect at times,” which has slowed the process of making vegetation especially flammable, Mr. Wachter said.

Since Jan. 1, about 214,000 acres have burned in California, compared with the five-year average of 444,000 for this time of year, according to the state fire agency, known as Cal Fire.

That number could start going up as vegetation across the state dries out in the heat.