Before crashing, the plane's tail was on fire as it circled in the air, one witness told The Associated Press.
"Then, I saw the plane crashing nose-down. It hit the ground causing a big explosion. The impact shook the ground like an earthquake. Then, plane pieces were scattered all over the agricultural fields," Ali Akbar Hashemi, a 23-year-old who was laying gas pipes in a nearby home, told AP by phone.
The impact blasted a deep trench in the dirt field, which was littered with smoking wreckage, body parts and personal items from the Tupolev jet, according to photos from the scene. Firefighters put out the flaming wreckage, which officials said was strewn over a 200 yard (meter) area. A large chunk of a wing was visible in footage of the scene, but much of the wreckage appeared to be in small shreds.
Iran has seen numerous crashes in recent years, usually blamed on poor maintenance. Iranian officials often blame U.S. sanctions that prevent it from updating American aircraft bought before the 1979 Islamic revolution and make it difficult to get European spare parts or planes as well.