Residents forced out of their homes by a northern Colorado wildfire were allowed to return on Wednesday after high winds failed to materialize and ground crews made more progress against the blaze.

About 100 people who were evacuated on Sunday were allowed to go home shortly after 2 p.m. Wednesday. The fire, in the foothills west of Loveland, has blackened 740 acres and destroyed two homes and an unknown number of vehicles.

Firefighters gained ground on fighting the blaze, however, with calmer-than-expected weather allowing crews to nearly double the amount of containment line. Fire managers said the blaze was 65 percent contained.

"Things really turned out very, very well," said Terry Krasko, a spokesman for the federal fire management team.

Firefighters had been told to expect winds of 20 to 25 mph Wednesday, but a revised forecast predicted only occasional gusts of that strength, with weaker winds overall.

Fire officials said they were ready for more challenging weather, pointing to the more than 550 people on the fire and "a small air force" of tankers and helicopters ready to drop fire retardant and water. The aircraft were brought to Colorado last week to fight a 10-square-mile fire that destroyed at least 166 homes west of Boulder.

Krasko said no retardant was dropped on the Loveland-area fire Wednesday. Some crews were expected to start leaving Thursday, but Krasko didn't know how many would take off.

At one point, firefighters thought the burned area was as big as 925 acres, or about 1 1/2 square miles, but they revised that downward after better mapping.

So far, the cost of fighting the fire is $1.86 million.

Electricity has been restored to about 95 percent of the homes and the rest will have power by Thursday, officials said.

Investigators said the fire was started accidentally by two residents who were burning leaves and other debris. Investigators turned over their findings to the Larimer County district attorney on Wednesday.

Prosecutors said they don't expect to decide whether to file charges until next week. The suspects' names haven't been released.

The blaze west of Boulder is completely encircled by fire lines, and firefighters expect to declare it fully controlled by Friday. The last of the evacuation orders were lifted at midday.

Investigators believe the Boulder blaze originated from a fire in a pit started by a volunteer firefighter, a longtime resident who lost his home. They say the firefighter had doused it with water and stirred the ashes to put it out, but strong winds reignited it.

A decision on whether to file charges isn't expected until next week. The firefighter's name hasn't been released.

Boulder, Larimer and at least six other Colorado counties and the west-Denver suburb of Lakewood have imposed bans or restrictions on outdoor fires. The federal Bureau of Land Management has placed fire restrictions on BLM land in all or part of eight counties in western and northwestern Colorado.

A small grass fire broke out Wednesday in a rural area near the town of Castle Rock, about 25 miles south of Denver.

South Metro fire department spokesman Andy Lyon said the fire grew to 13 acres before it was contained. Firefighters suspect it was started by a passing train.

Conditions were slightly better in western Colorado. Federal authorities plan to light a prescribed 400-acre burn near Paonia on Thursday.