"If the plane had been hit by a missile, the area, in which its pieces were scattered, would be very large, but all parts were in the one place", CAO chief Ali Abedzadeh said.
He added that the investigation team was still waiting for information from the aircraft's black box.
Abedzadeh also said that the plane’s pilot had called the control tower prior to turning back toward the airport but that the engine caught fire in mid-air and the plane crashed about two minutes later.
The Boeing 737 crashed on Wednesday near Tehran, shortly after takeoff, killing all 176 people on board, including citizens from Iran, Canada, and Ukraine. The incident occured shortly after Iran's missile attack on American facilities in Erbil and the Ayn al-Asad Air Base in Iraq.
Ukrainian President Volodymyr Zelensky earlier stated that claims about the plane being shot down by a missile could not be excluded, but insisted that they remained unconfirmed. The president added that he would be holding talks later on Friday with US Secretary of State Mike Pompeo regarding the ongoing investigation into the plane crash.
The head of Iran’s Civil Aviation Organization Accident Department, Hassan Razai, said that Iran will begin analysing Boeing 737's black box on Friday.