RENO ­— An “extremely remorseful” elderly man admitted Friday he accidentally started a brush fire that exploded into a wall of flames and destroyed 29 homes when he improperly discarded fireplace ashes at his home south of town, fire officials said.

Reno Fire Chief Michael Hernandez told reporters that investigators determined the cause of the blaze that burned nearly 3,200 acres and forced the evacuation of up to 10,000 people at the fire’s peak Thursday evening.

“He came forward on his own accord,” Hernandez said.

“He has given statements to our investigators as well as law enforcement officers. He is extremely remorseful,” he said.

Washoe County Sheriff Mike Haley said the case will be forwarded to the district attorney for consideration of formal charges. In addition to the potential for charges as serious as felony arson, the man could be ordered to pay the cost of fighting the fire, which already totals $690,000, authorities said.

Washoe County Manager Katy Singlaub said she expects costs to rise into the millions of dollars.

Investigators had tracked the origin of the fire to a location in East Lake on the north end of the Washoe Valley, where the man lives.

Hernandez said he couldn’t comment more other than to say the man was elderly.

Hernandez also confirmed a 93-year-old woman had been found dead in a home that had suffered fire damage Thursday but they have not confirmed the cause of death.

Responders to the Washoe Drive Fire were turning a corner Friday evening, looking more at the impending threat of heavy rain and possible flash flooding while mopping up after the devestating blaze that destroyed 29 structures in the Washoe Valley area.

By 4:20 p.m., fire crews had contained 65 percent of the fire, according to spokeswoman Tia Rancort of the Sierra Fire Protection District.

“The fire is pretty much knocked down,” Rancort said. “We’re workng on mopping up stuctures and the interior.”

Utility workers had restored power to 2,000 customers who had been affected by a power outage through the night. Some 200 remained without power, Rancort said.

“Our goal today was to get power restored,” Rancort said.

Just as fire crews were getting control of the blaze, officials at the National Weather Service issued a flash flood warning for the Reno/Carson City area. A powerful Pacific storm was set to impact western Nevada by the evening. Ahead of the system, warm air was to raise snow levels above 7,500 feet.

Rain was to begin by 7 p.m. and was expected to be heavy in the evening and night as a cold front moved through the recent burn areas of the Caughlin and Washoe Drive fires. Burn areas are extremely suseptible to flash flooding.

Snow levels were expected to drop by early today and decrease the flash flood threat, according to the National Weather Service.

A few more than 3,179 residents remained evacuated Friday evening, a huge drop from the 10,000 initially asked to leave their homes Thursday night. The Red Cross first opened a shelter at Damonte Ranch High School, ready to house those in need, but found that many people either had other places to stay or were allowed back home. The agency closed the shelter Friday morning.

“We closed the shelter today because the bulk of evacuees had been let back in and the others had found alternative lodging,” said Carla Werner, Red Cross spokeswoman in Reno.

Sparks Fire Department reported all firefighters and equipment were back at the station Friday afternoon after assisting with the fire. Sparks joined with teams from all over northern Nevada. A total of 700 personnel addressed the incident Friday.

Drivers continued to be detoured throughout the northern Nevada area while U.S. 395 remained closed between the Summit junction and north Carson City. It was expected to re-open by 10 p.m. Friday.