GRAYLING TOWNSHIP, Mich. (AP) — A Michigan wildfire that's burned more than 3 square miles (7.7 square km) amid hot, dry conditions was sparked by a campfire, the state Department of Natural Resources said Sunday.

The Wilderness Trail Fire in Crawford County began about 1 p.m. Saturday near Staley Lake in Grayling Township and was traced to a campfire on private property, the department said in a Sunday update.

Michigan Department of Natural Resources said the fire, which has scorched more than 2,000 acres (809 hectares), was 85% contained by Sunday morning after the agency's fire crews and partner agencies worked through the night to combat the blaze.

“The crews were working in hilly, sandy terrain and that was difficult. Weather conditions also were hot, dry and windy,” Mike Janisse, an incident commander with the Michigan DNR, said in a statement.

On Saturday, the wildfire pushed west and southwest, burning through stands of jack pine, mixed pines and oak, threatening multiple buildings. Heavy smoke from the fire prompted the closure of Interstate 75 from Saturday afternoon until shortly before midnight, the department said.

Emergency evacuations were issued for the fire area but residents were allowed to return to their homes late Saturday.

The department said the fire danger remains very high to extreme in most parts of Michigan and those conditions are expected to persist amid lingering hot, dry conditions.

Janisse said officials are not currently granting burn permits for yard debris due to the fire risk. He urged residents “to refrain from burning until we get significant rain.”

Grayling Township is located about 150 miles (241 km) north of Lansing.