WHITERIVER, Ariz. — Over 100 firefighters and other personnel are battling a wildfire burning in a remote area of the Fort Apache Indian Reservation and the Apache-Sitgreaves National Forests in eastern Arizona.

The Bureau of Indian Affairs says cause of the fire that started Wednesday that has burned approximately 400 acres (162 hectares) of pine and grass by Thursday isn’t known.

BIA spokeswoman Candy Lupe says no structures are threatened and that no injuries have been reported.

Four 20-member hotshot crews and two other crews are assigned to the fire, along with water tenders and other equipment.

The BIA says a Type 3 fire management team has been assigned to assume command of the fire Thursday evening.