CNN  — 

All 65 people on board a passenger plane that crashed Sunday in a mountainous region of southern Iran are presumed dead, the airline said.

The Aseman Airlines plane was flying from Tehran to the southwestern city of Yasuj when it disappeared 50 minutes into the flight, according to a post on the airline’s Instagram account.

The flight, which departed at 7:55 a.m. local time (11.25 p.m. ET Saturday), crashed in Kohangan village, 120 kilometers (74 miles) from Semirom town, authorities told Iran’s Fars News Agency .

Earlier reports said 66 people had died in the crash, but one would-be passenger did not board the flight, Aseman Airlines confirmed Sunday.

Iran’s Supreme Leader Ayatollah Ali Khamenei and President Hassan Rouhani expressed their condolences to the victims and their families, ordering officials to spare no efforts in their rescue operation, the state-run Islamic News Agency reported.

The ATR aircraft, a twin-engine turboprop typically used for short-distance regional flights, hit the Dena Mountains, the report said.

Aseman’s public relations chief, Mohammad Tabatabaie, told Iran’s semi-official news agency ISNA that until the wreckage was recovered it was not possible to confirm all deaths.

“Given the special circumstances of the region, we still have no access to the spot of the crash and therefore we cannot accurately and definitely confirm the death of all passengers of this plane,” he said.

Those aboard included 59 passengers, two flight attendants, two pilots and two members of security forces.

Aseman Airlines posted an image of the plane involved in the crash on its Instagram account.

Pilot Hojatollah Fooled successfully landed a similar plane after an engine problem in 2013, the airline said in an Instagram post.

It described Fooled as “very experienced.”

“On a previous flight from Yasuj to Tehran in 2013 he had an issue where the second engine of the ATR72 went out,” said the post. “But he manged to land the plane safely at Yasuj airport.”

Twenty rescue teams have been dispatched to the crash site. One helicopter earlier forced to turn back due to bad weather.

“This is a snow-covered mountainous area, much like the Rockies in America or the European Alps,” CNN Senior International Correspondent Sam Kiley said. “Any rescue operation will depend entirely on the weather.”

Several flights from Tehran were disrupted Sunday due to bad weather, according to IRNA.

And at Abadan International Airport in southwestern Iran, two domestic flights were canceled due to pollution, which reduced visibility range to two meters, IRNA added.

CNN’s Shirzad Bozorgmehr and Amir Daftari reported from Tehran. Samantha Beech and Jonny Hallam reported from Atlanta.