Iron Dog started February 17 at Big Lake, Alaska with thousands of spectators gathered to wish the 39 Pro Class teams their best.

The weather was mild and the race started with out issues.

A plane supporting racers in the race crashed Sunday night near Rainy Pass Lodge on Puntilla Lake, according to the Alaska Dispatch. The aircrafts two passengers were, Robert D. Stone, age 44, and Jason A. Wichman, age 31. Wichman was supposed to race the 2013 Iron Dog, but pulled out due to injury. They are being treated for critical injuries in Anchorage.

Fans can track the racers' progress on the Iron Dog's website.