RENO, Nev. — Washoe Valley evacuees started returning Tuesday to their homes north of Carson City, where a raging wildfire destroyed 23 homes last week.

Fire officials told the Washoe County Board of Commissioners it cost about $4 million to battle the blaze, which charred about 3.5 square miles along the Sierra’s eastern front and is expected to be fully contained by Thursday.

They said they were fortunate more houses didn’t burn, thanks largely to the quick, unified attack on the flames that broke out early Friday followed by heavy weekend rains. “One of the characteristics of our country and our community is how we come together during a time of disaster,” said Charles Moore, chief of the Truckee Meadows Fire Protection District.

The same Pacific storm packing the powerful winds that fanned the fire ended up dropping more than 2.75 inches of rain on the area during a 24-hour period beginning Sunday.

Four firefighters were treated for smoke inhalation, but no serious injuries were reported. The cause of the fire remains under investigation. Fire officials say it started in the same area where a prescribed burn was conducted a week earlier.

Forest Service team leader Kim Martin said winds were gusting up to 80 mph during the early stages of the fire. Martin said firefighters will continue to monitor the perimeter around the clock, but that it was 90 percent contained as of Tuesday. She made a presentation to the commissioners at a meeting in Reno where they voted to renew an automatic mutual aid agreement between the city of Reno and the fire protection district through 2019.

“This agreement is about working together in the best, most efficient way possible to keep our citizens safe,” Moore said.

Nearly 1,000 firefighters battled the blaze, including some from as far away as the San Francisco Bay Area.

“It was incredible to see firefighters from several agencies with hundreds of engines lined up working side by side seamlessly,” Commissioner Bob Lucey said. “Unfortunately, we did lose 23 homes, but we could have lost many more.”