At least 38 people are reported dead, including seven children, after a passenger plane crashed on takeoff from Tehran's Mehrabad international airport.
Iranian media issued differing casualty reports, with some reports suggesting nine people were injured, although details of their condition was not immediately available.
Iran's state-run had earlier reported that all 48 people aboard had died.
Iran's Press TV cited initial reports blaming "engine failure."
The Iran-140 plane was heading to the eastern city of Tabas.
Iranian media initially reported that the pilot was a Ukrainian national, but the Ukrainian Foreign Ministry later disputed that, saying it had no citizens aboard.
The Iran-140 is a 52-seat plane produced in Iran with Ukrainian technology. It is a version of the Antonov An-140.
Iran has suffered a series of plane crashes, blamed on its ageing aircraft and poor maintenance record.
In 2011, an Iran Air Boeing 727 broke to pieces on impact while trying an emergency landing in northwestern Iran, killing nearly 80 people.
In 2009, a Russian-made aircraft crashed in northwest Iran, killing all 168 on board.
Based on reporting by AP, AFP, and Reuters