It was the second time in two months that a military plane crashed in Iran while attempting an emergency landing.
In Monday's crash, the plane was trying to land at Oroumieh, about 560 miles northwest of Tehran near the Turkish border, the media reported.
Gen. Masoud Jazayeri, spokesman for the Revolutionary Guards, told state radio that various factors were to blame: both of the plane's engines had failed; its landing gear had jammed, preventing the wheels from fully deploying; and there was snow and poor visibility at the time.
Jazayeri said that Gen. Ahmad Kazemi, commander of the ground forces of the Revolutionary Guards, and 10 other officers were killed, the official Islamic Republic News Agency reported.
In addition, state television said two crew members were killed. However, the news agency and state radio said the plane had a crew of three. The discrepancy could not be immediately explained.
State television said the plane was a Falcon jet and was owned by the Guards. It was made by the French company Dassault.
Kazemi, a veteran of the 1980-88 war with Iraq, was appointed commander of the Guards' ground forces in August in a reshuffle after President Mahmoud Ahmadinejad took office.
The Revolutionary Guards are separate from the regular Iranian armed forces. Founded after the 1979 Islamic Revolution, the Guards have their own air, naval and ground components. Ahmadinejad is a former commander in the Guards.
Iran has a history of aircraft accidents involving a heavy loss of life. The government has blamed the U.S. trade embargo, which makes it impossible for Iran to buy parts for its old U.S.-built aircraft. Critics have also said planes are poorly maintained.
On Dec. 6, a military transport plane crashed into a 10-story apartment building near Tehran's Mehrabad airport, killing 115 people. The plane, a U.S.-made C-130, had suffered engine trouble and the pilot was returning to the airport when the aircraft suddenly lost height and slammed into the building. Most of the passengers were Iranian journalists.
In 2003, a Russian-made Ilyushin-76 carrying Guards members crashed in the mountains of southeastern Iran, killing 302 people.
In 2002, a Russian-made Tupolev-154 crashed in the mountains of western Iran, killing all 119 people on board.