At approximately 0730 Mountain time, the airplane was destroyed when it impacted trees and terrain while maneuvering approximately 20 miles east of Spanish Fork, Utah. Visual conditions prevailed; the pilot and one passenger on board the airplane were seriously injured. Two other passengers had minor injuries. According to one of the passengers, the airplane was flying in a canyon. As the pilot tried to pull up, the engine sputtered a little bit and struck trees. The engine sounded like it was bogging down before the tree strike.