Updated 8:26 PM EST
RENO, Nev. - A firefighter suffered first and second-degree burns and an elderly man died of a heart attack while trying to flee a sudden wildfire that spread through the Nevada Sierra foothills and roared into Reno on Friday, blanketing upscale houses, horse pastures and mountain roads in smoke plumes, amber flames and flying embers.
Authorities said the worst was likely over, but warned a change in the furious northern winds could refuel the sprawling fire that sent thousands of families fleeing their homes in the middle of the night and blanketed the region's mountain roads in flames. At least 25 properties were damaged and destroyed.
Fire Chief Mike Hernandez said flames still endanger some areas, but firefighters had largely contained the blaze that sent nearly 10,000 people from their homes in the middle of the night.
"We are actually backtracking and going over areas that have burned and extinguishing hot spots," Hernandez said.
The Federal Emergency Management Agency has declared the fire a major disaster.
Roughly 100 Nevada National Guard members were assisting local law enforcement in checking homes and keeping people out of the evacuated area. Health officials urged residents to stay inside and reduce physical activity, warning that the dust and smoke were adding to pollution levels in the affected regions and downwind neighborhoods.
Sixteen people were hospitalized, many for smoke inhalation. A 74-year-old man died of a heart attack while trying to leave his home.
The cause of the blaze wasn't known, but a downed power line or homeless encampments in the area might be to blame, Hernandez said. He said the region is also a popular area for teenagers who might have started the fire to stay warm.
Growing snow flurries and dropping temperatures late Friday afternoon stroked hopes that the remaining showers of ember and ash would die down quickly.
At least 400 firefighters from as far as 260 miles away flocked to Reno early Friday as multiple fires roared from the Sierra Nevada foothills in northwestern Nevada and spread to the valley floor. Police went house-to-house, pounding on doors and urging residents to evacuate in the dark of the night.
"The whole mountain was on fire," said Dick Hecht, who said when he escaped from his home with his wife, it was so windy he could barely stand. "It was so smoky, you couldn't hardly see."
The couple tried to return to their home before morning, but they were turned back by high winds and erupting flames. As they made their way back down the mountain roads, flames burned less than 40 yards from their vehicle.
Gusts of up to 60 mph grounded firefighter helicopters and made it difficult for firefighters to approach Caughlin Ranch, the affluent subdivision bordering pine-forested hills where the fire likely began after 12:30 a.m.
The strong winds combined with area's dry terrain helped the fire spread from 400 acres to 2,000, or more than 3 square miles. Firefighters said their efforts spared 4,000 homes, but that the disaster would likely cost multi-millions of dollars. The gusts were comparable to the Santa Ana winds that often aggravate and spread wildfires in the hills surrounding Los Angeles, officials said.
"The wind is horrific," said Reno spokeswoman Michele Anderson. "We just watched a semi nearly blow over on the freeway."
Evacuated families were shaken up by the fire.
"I thought it was an earthquake," Darian Thorp told the Reno Gazette-Journal. "We could see it from our window. ... Then I could see it from both sides. It was all around us."
Reno resident Kathy Harrah said she was panicking when an officer knocked on her door in the middle of the night. She ordered her son rip a computer out of a wall and load up household items in their truck as they evacuated.
"I was watching the fire all night," Harrah told the Reno-Gazette-Journal. "I didn't know it was going to get this bad."
John and Maggie Givlin were among those watching a television at the shelter at Reno High School Friday morning, scanning the screen for details on whether the home they left behind was safe. They already were preparing to flee when a police officer knocked on their door at about 1:30 a.m.
"I smelled smoke and got out of bed and the electricity was out," said John Givlin, a retired civil engineer who has lived there about eight years. "I looked out the front window and saw the glow over the hill before us."
He and his wife made their way out of their home with a flashlight. Outside, flames billowed in every direction.
More than 150 people had filled two shelters set up at area high schools by midmorning.
"The people are in a state of shock and are hanging in there," Gov. Brian Sandoval said.
More than 4,000 NV Energy customers lost power as poles and electrical wires were scorched and knocked down, said spokeswoman Faye Andersen. Utility workers were not being allowed into the fire area.
Reno Mayor Bob Cashell said evacuees could start returning to their homes at noon Saturday. Cashell said a number of local hotel-casinos were offering discounted rooms to displaced residents.
"These next 24 hours, with all the power lines down and everything else, it is still a very, very dangerous area," he said.
School buses were on standby to help with evacuations. At least 90 schools were closed for the day to clear the roads of school traffic and make way for emergency workers.
The U.S. Postal Service suspended delivery to the area for the day and the state high school athletic association moved its football playoffs from Friday night to Monday.