A military airplane with 94 people on board has crashed into a 10-storey appartment building in the Iranian capital Tehran.
All of the people on the plane were killed, and officials are worried people on the ground have died too.
The plane had just taken off from the Mehrabad airport when the pilot turned back and tried an emergency landing.
Emergency services went to the scene and the area was sealed off while the fires were extinguished.
Tehran state radio said at least 34 people in the building have been killed and many more injured.
There are worries that a number of those maybe children, as many schools were closed in the city on Tuesday because of really bad smog.
Iran has a poor record when it comes to the safety of their airplanes, with four serious crashes in the last five years.