Some 65 people have been killed after the plane they were travelling on crashed in fog in a mountainous region in southern Iran.
A spokesperson for the airline said the flight was carrying 59 passengers, including one child, and six crew members.
Another passenger was meant to be on the flight, but missed the plane, state-run media reported.
The Aseman Airlines plane crashed into Mount Dena, Mohammad Taghi Tabatabai, a spokesperson for the company said.
It is thought that the plane was an ATR-72 and was flying from Tehran to the southern Iranian city of Yasuj, when it crashed close to its destination almost 500 miles south of the capital.
State television reported that due to foggy conditions, rescue helicopters were unable to reach the crash site.
Flight EP3704 took off from Tehran at 4.33am and gave its last signal at 5.55am, when the flight was at 16,975 feet and was descending.
Aseman Airlines is a semi-private air carrier headquartered in Tehran that specialises in flights to remote airfields across the country. It also flies internationally.
It is banned from flying in the European Union due to safety concerns.
The Iranian Red Crescent said it has deployed to the area, which was quite foggy at the time of the crash. Authorities said they would be investigating.
Under decades of international sanctions, Iran's commercial passenger aircraft fleet has aged, with air accidents occurring regularly in recent years.
Following the 2015 landmark nuclear deal with world powers, Iran signed deals with both Airbus and Boeing to buy scores of passenger planes.