All 65 people aboard an Aseman Airlines plane were feared dead when it slammed into Mount Dena in central Iran Sunday during a bout of bad weather, authorities told the Iranian state broadcaster.
But there was so much fog and rain that rescue crews had been unable to reach the crash site via helicopter and were hoping a drone could aid in their search, reports IRNA, the country's official news agency.
An airline spokesman had initially told state television that everyone was killed in the crash. But then the airline issued a statement saying that because it could not access the crash site, it could not "accurately and definitely confirm" everyone died, reports Reuters.
The twin-engine turboprop plane, used for short-haul flights, took off from Tehran before 8 a.m. local time Sunday en route to the city of Yasuj, some 450 miles south of Tehran, IRNA reports.
A short time later, the plane disappeared from radar screens.
It went down near the city of Semirom, IRNA reports, during "extreme weather." But the cause of the crash remains unclear.
There were thought to be 60 passengers — including one child — and six crew members on board, the state broadcaster reported.
But Reuters reports that while the airline had first said 66 people were on the flight, they later amended the number to 65, as one passenger had missed the flight.
The New York Times reports that plane crashes have been a regular occurrence in Iran after years of international sanctions left the country with an ageing commercial passenger fleet.
In 2014 a regional plane crashed upon takeoff in Tehran killing all four dozen people on board.
And more than 100 people died in 2005, when a military transport plane crashed into a Tehran apartment building, killing everyone on board as well as others on the ground.
Iran's state broadcast says after sanctions were lifted in 2016, French-Italian plane-maker ATR struck a deal with Iran for the delivery of 20 ATR passenger planes for short-haul routes; but so far fewer than half of the planes have been delivered.
Iran has also struck a deal with Boeing to buy more than 100 aircraft.
In the past, President Trump has threatened to scrap the Obama-era nuclear deal and issue new sanctions.