An Iranian air force cargo plane landing at the wrong airport crashed outside Tehran, killing 15 people on board, state-run Fars news agency reported.
Authorities did not immediately offer a reason for the crew's decision to land there, though they said the crew had declared an emergency prior to land.
Fath airport is near Karaj in the central province of Alborz.
"We don't have clear information about the details of the crash", said the head of Iran's emergency department, Pir Hossein Koolivand.
Conservative news agency Tasnim said it was a military cargo plane carrying meat from the Kyrgyzstan capital of Bishkek.
Iran's Red Crescent Society has dispatched eight rescue teams, including several ambulances and a helicopter, to the site.
The plane overshot the runway during its landing, Iran's aviation organisation spokesman Reza Jafarzadeh told state broadcaster IRIB. AFP.
Iranians often use the word "martyrdom" for those who die in war or national service, suggesting the aircraft may have belong to the air force.
It was later confirmed it belonged to Iran's air force.
Earlier Iranian state media said 10 people were on board of the crashed plane.