Tehran, Iran, AFP — Iranians on Monday mourned the death of President Ebrahim Raisi whose helicopter crashed into a fog-shrouded mountain, setting off a period of political uncertainty in the Islamic republic.

Raisi, 63, his foreign minister and seven others died when the aircraft went down on Sunday in a remote area of north-western Iran, where the wreckage was found on Monday morning.

The ultraconservative Raisi had been in office since 2021, a turbulent time during which Iran was rocked by mass protests, an economic crisis deepened by United States sanctions, and armed exchanges with arch-enemy Israel.

Supreme leader Ayatollah Ali Khamenei, who wields ultimate power in Iran, declared five days of mourning and said Vice-President Mohammad Mokhber, 68, would assume interim presidential duties until elections are held within 50 days.

State media reported late on Monday that the elections would be held on June 28.

“The Iranian nation has lost a sincere and valuable servant,” said 85-year-old Khamenei, whom Raisi had been expected by many observers to one day succeed .

Thousands of mourners massed in central Tehran’s Valiasr Square to pay their respects to Raisi and to Foreign Minister Hossein Amir-Abdollahian.

Funeral rites are set to start today in Tabriz, East Azerbaijan province, for them and the other victims — three crew, two bodyguards, an imam and a provincial governor — before Raisi’s body will be taken to Tehran.

A funeral procession will take place in the capital on Wednesday morning.

Iran’s military chief of staff Mohammad Bagheri ordered “a high-ranking committee to launch an investigation into the cause of the president’s helicopter crash”.

State TV broke the news early on Monday that “the servant of the Iranian nation, Ayatollah Ebrahim Raisi, has achieved the highest level of martyrdom”, showing pictures of him while a voice recited from the Koran.

Flags soon flew at half-mast and a black banner was hoisted at a major Shiite shrine in the city of Qom south of Tehran.

Iranian authorities first raised the alarm on Sunday afternoon when they lost contact with Raisi’s helicopter as it returned from a border meeting with Azerbaijan’s President Ilham Aliyev to inaugurate a dam.

Only two of the convoy’s three helicopters landed in Tabriz, setting off a massive search and rescue effort, with multiple foreign governments soon offering help.

Interior Minister Ahmad Vahidi at first spoke of a “hard landing” and urged citizens to ignore hostile foreign media channels and get their information “only from State television”.

Guards, army and police personnel joined the search as Red Crescent teams trudged up a steep hillside in the rain while rows of emergency services vehicles waited nearby.

As the sun rose Monday, rescue crews said they had located the destroyed Bell 212 helicopter, with no survivors.

State TV reported that the aircraft had “hit a mountain and disintegrated” on impact, and the Red Crescent soon confirmed that “the search operations have come to an end”.