The helicopter crash that killed Irans president and foreign minister has sent shock waves around the region.

Iranian state media said on Monday that President Ebrahim Raisi, the countrys foreign minister Hossein Amirabdollahian and others have been found dead at the site after an hourslong search through a foggy, mountainous region of the countrys northwest.

Heres what we know so far.

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

The helicopter was carrying Raisi, Amirabdollahian, the governor of Irans East Azerbaijan province and others officials, according to the state-run IRNA news agency.

Raisi was returning on Sunday after traveling to Irans border with Azerbaijan to inaugurate a dam with Azerbaijans President Ilham Aliyev when the crash happened in the Dizmar forest in Irans East Azerbaijan province.

IRNA said the crash killed eight people in all, including three crew members aboard the Bell helicopter, which Iran purchased in the early 2000s. Aircraft in Iran face a shortage of parts, often flying without safety checks over Western sanctions. Because of that, former Iranian Foreign Minister Mohammad Javad Zarif sought to blame the United States for the crash.

The U.S. has yet to comment publicly on Raisis death.

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, Koulivand said, according to IRNA.

How was the crash site found?

Early on Monday, Turkish authorities released what they described as 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 put 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 after, state TV in an on-screen scrolling text said: There is no sign of life from people on board.

How will Raisi’s death impact Iran?

Raisi was seen as a protg to Irans supreme leader Ayatollah Ali Khamenei and a potential successor for his position within the countrys Shiite theocracy.

Under the Iranian constitution, if a president dies, the countrys 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 Raisis 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 Azerbaijans 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.