An Aseman Airlines flight carrying dozens of passengers from Tehran to Yasuj in Iran has crashed in a mountainous area, according to reports.
There were anywhere from 60 to 100 people on board the domestic flight, media in Iran are reporting.
The ATR 72 plane vanished from radar about 20 minutes after taking off at about 5am local time.
Witnesses told local media that it appeared the plane was trying to make an emergency landing on a pasture before it crashed.
A crash site was found near Semirom in Iran's central Isfahan province, but a rescue helicopter was unable to immediately land due to bad weather.
Rescue teams were sent to the site to search for survivors.
However the rescue effort was hampered by the remote location of the crash site and dense fog.
Reports stated that it was impossible for ambulances to reach the mountainous site, so teams had to be sent in by helicopter.
There were conflicting reports on the number of passengers and crew on board, with some media putting the total at about 60 and others at 100.
Aseman Airlines is the third largest carrier in Iran and is based in the capital Tehran (Mirror.co.uk)