Boulder, Colorado (CNN) -- Firefighters reported progress Friday night after battling a Colorado wildfire that had been pushed into the city of Boulder by blustery winds earlier in the day.
"Things are going very well," said Terry Krasko, a spokesman for the team battling the blaze.
Krasko said that firefighters expected to be "done" with the Fourmile Canyon fire in three to five days.
"We are looking for this thing to wind down very quickly at this point," he said.
The fire, which started Monday morning, has charred more than 6,400 acres of countryside and destroyed 172 structures -- 160 of which were homes -- on Boulder's west side.
Krasko said about 3,000 people were evacuated, and Boulder County Sheriff's Cmdr. Rick Brough said that about 2/3 of those had returned. About 600 homes in the "burn area," Brough said, are still empty.
Krasko added that some areas where residents have returned are without electricity because utility lines in the burn area have not yet been repaired. Repairs are under way, he said.
Boulder is about 35 miles northwest of Denver, at the eastern edge of the Rocky Mountains. There have been no deaths or injuries, and four people who had been listed as unaccounted for have been contacted and are unhurt, Brough said.
Brough said the investigation into the cause of the fire was open.
"We do still have investigators working on the cause," he said. "Fire investigations take some time."
Colorado Gov. Bill Ritter declared a state of emergency this week, throwing $5 million into the battle to save homes and forests in the canyon.