The airplane collided with trees and terrain at about 1600 Pacific time and was substantially damaged by impact and a post-crash fire. The Private pilot and his passenger were fatally injured. The aircraft departed from the pilots private airstrip at an unknown time. The airstrip was located within one-quarter of a mile northwest of the accident site. Witnesses near the accident site reported that the aircraft was seen traveling in an easterly direction, very low and near the tree line just before the collision. The witnesses reported that the engine was running, but seemed like it was strained or not at full power.