The helicopter crash that killed Iran’s President and foreign minister has sent shockwaves throughout the region.

Iranian state media said President Ebrahim Raisi, foreign minister Hossein Amirabdollahian and others were found dead at the site after a search through a foggy, mountainous region of the country’s north-west.

Here is what we know so far.

– Who was on board the helicopter and where were they going?

The helicopter was carrying Mr Raisi, Mr Amirabdollahian, the governor of Iran’s East Azerbaijan province and other officials and bodyguards, according to the state-run IRNA news agency.

Mr Raisi was returning on Sunday after traveling to Iran’s border with Azerbaijan to inaugurate a dam with Azerbaijani President Ilham Aliyev when the crash happened in the Dizmar forest in Iran’s East Azerbaijan province, under circumstances that remain unclear.

– How did the search operation go?

Iranian officials have said the mountainous, forested terrain and heavy fog impeded search and rescue operations, which began on Sunday.

The president of the Iranian Red Crescent Society, Pir-Hossein Koulivand, said 40 search teams were on the ground despite “challenging weather conditions”.

Because of the bad weather, it was “impossible to conduct aerial searches” via drones, the official said, according to IRNA.

– How was the crash site found?

In the early hours of Monday, Turkish authorities released drone footage showing what appeared to be a fire in the wilderness that they “suspected to be wreckage of a helicopter”.

The coordinates listed in the footage placed the fire some 12 miles south of the Azerbaijan-Iranian border on the side of a steep mountain.

Footage released by IRNA showed what the agency described as the crash site, across a steep valley in a green mountain range.

Soldiers speaking in the local Azeri language said: “There it is, we found it.”

Shortly afterwards, state TV reported in an on-screen scrolling text: “There is no sign of life from people on board.”

– How will Raisi’s death affect Iran?

Mr Raisi was seen as a protege to Iran’s supreme leader Ayatollah Ali Khamenei and a potential successor for his position within the country’s Shia theocracy.

Under the Iranian constitution, if a president dies, the country’s first vice president – in this case, 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.

– What has the international reaction been?

After the news first broke of the search operation, countries including Russia, Iraq and Qatar made formal statements of concern about Mr Raisi’s fate and offered to assist in the search.

Azerbaijani President Aliyev offered any support necessary. Relations between the two countries have been chilly due to Azerbaijan’s diplomatic relations with Israel, Iran’s regional arch-enemy.

Saudi Arabia, traditionally a rival of Iran although the two countries have recently made a rapprochement, said it stands by Iran “in these difficult circumstances”.

There was no immediate official reaction from Israel. Last month, following an Israeli strike on an Iranian consular building in Damascus that killed two Iranian generals, Tehran launched hundreds of missiles and drones at Israel.

They were mostly shot down and tensions have apparently since subsided.