What do we know so far about the mysterious crash of the helicopter carrying Iran's president?

The apparent crash of a helicopter carrying Iran's president and foreign minister on Sunday sent shock waves around the region.

The apparent crash of a helicopter carrying Iran's president and foreign minister on Sunday sent shock waves around the region.

Details remained scant in the hours after the incident, and it was unclear if Iranian President Ebrahim Raisi and the other officials had survived.

Here's what we know so far.

The helicopter was carrying Iranian President Ebrahim Raisi, the country’s Foreign Minister Hossein Amirabdollahian, the governor of Iran’s East Azerbaijan province and other officials and bodyguards, according to the state-run IRNA news agency. Raisi was returning from a trip to Iran’s border with Azerbaijan earlier Sunday to inaugurate a dam with Azerbaijan’s President Ilham Aliyev, the news agency said.

The helicopter apparently crashed or made an emergency landing in the Dizmar forest between the cities of Varzaqan and Jolfa in Iran's East Azerbaijan province, near its border with Azerbaijan, under circumstances that remain unclear. Initially, Interior Minister Ahmad Vahidi said the helicopter “was forced to make a hard landing due to the bad weather and fog.”

Iranian officials have said the mountainous, forested terrain and heavy fog impeded search-and-rescue operations. The president of the Iranian Red Crescent Society, Pir-Hossein Koulivand, said 40 search teams were on the ground in the area despite “challenging weather conditions.” The search is being done by teams on the ground, as “the weather conditions have made it impossible to conduct aerial searches” via drones, Koulivand said, according to IRNA.

Raisi is seen as a protégé to Iran’s supreme leader Ayatollah Ali Khamenei and a potential successor for his position within the country’s Shiite theocracy. Under the Iranian constitution, if he died, the country’s first vice president, Mohammad Mokhber, would become president. Khamenei has publicly assured Iranians that there would be “no disruption to the operations of the country” as a result of the crash.