HELENA, Mont. (AP) — Hundreds of Montana residents who fled their homes because of a four-day wildfire were allowed back Tuesday to gather important belongings as Oregon authorities warned of unhealthy air because of another blaze that sent smoke wafting over a key highway and drifting more than 50 miles (80 kilometers) to the state’s border with California.

In Montana, fire officials expressed frustration that about half of the people told to leave 400 homes and two state campgrounds threatened by the fire did not heed the evacuation warning issued over the weekend.

“We need to try to figure out the mindset of people,” Mike DeGrosky, chief of the Montana Department of Natural Resources and Conservation’s Fire Protection Bureau, told the Great Falls Tribune newspaper. “It wasn’t like they were soft-selling the issue, and we still didn’t get a good response.”

The fire started on federally owned land near a location that has been used as an informal shooting range and is believed to have been caused by a person, though investigators have not determined the precise cause.

About 360 people were fighting the fire, including 160 digging fire lines in an effort to contain the blaze. They were helped somewhat by light rain that fell Monday evening that increased humidity in the area, officials said. A brief thunderstorm Tuesday sparked several small new fires in the area, the Independent Record newspaper in Helena reported.