Tehran, Iran — An Iranian passenger plane crashed in the mountains of southern Iran on Sunday, killing all 65 people on board, officials said. Aseman Airlines Flight 3704 was flying from Tehran’s Mehrabad International Airport to the southern city of Yasuj and crashed near the 14,000-foot Dena mountains, airline officials said.

The ATR-72, a twin-engine turboprop aircraft used for short distances, went down about 50 minutes into the 350-mile journey, said a spokesman for the airline, Mohammad Taghi Tabatabaei.

Officials earlier said 66 people were aboard the plane, but the state-run IRNA news agency reported later that one person listed as a passenger had missed the flight. There were 59 passengers and six crew members on the flight, the news agency said.

The cause of the crash was not known, although airline officials blamed bad weather in the mountains. Rescue workers said they were having difficulty landing air ambulances near the crash site because of heavy fog.

State-run Iranian media reported that the same aircraft — one of six in the airline’s fleet — had technical problems during a flight out of Tehran 23 days ago, forcing the pilot to return to Mehrabad.

The Iranian Students News Agency reported that the captain of that flight, Hojjatollah Foladi, was flying the plane that crashed Sunday.

Aseman Airlines, a semi-private carrier and one of the country’s largest, flies mainly to domestic destinations but also operates international flights to Istanbul, Kuwait City and Dubai, United Arab Emirates.

Hobbled for decades by sanctions and trade restrictions, Iran’s domestic airline industry has one of the world’s oldest passenger fleets.

Poor condition of aircraft is often cited as a reason Iran suffers from one of the world’s worst air safety records. Since 1979, about 1,700 people have died in more than 90 aircraft-related accidents, according to the Flight Safety Foundation.