Three volunteers working the Iditarod Trail Sled Dog Race are being flown to Nome for medical treatment after their small plane went down.

Alaska State Troopers say the three were on board a Cessna 180 used by the Iditarod air force, pilots who volunteer their time and planes for the 1,100-mile race.

Trooper Sgt. Andrew Merrill says the injuries are not believed to be life-threatening.

Merrill says the plane went down Tuesday about 16 miles outside of White Mountain, a checkpoint 77 miles from the Nome finish line.

The cause of the mishap is unknown.