What we know about Iranian president's helicopter crash

Iranian media said Monday that Iranian President Ebrahim Raisi had died after his helicopter crashed in a mountainous region of the country.

Here is what we know so far:

What happened?

On Monday, Iranian media outlets declared Raisi dead after his helicopter crashed, though there has been no official confirmation yet.

"The president of the Islamic Republic of Iran, Ayatollah Ebrahim Raisi, had an accident while serving and performing his duty for the people of Iran and was martyred," said the local Mehr news agency, with other outlets also reporting the news.

On Sunday, Iranian state television had reported that a helicopter carrying Raisi had been in an accident in the Jolfa region of East Azerbaijan province amid poor weather conditions.

The accident happened in the mountainous protected forest area of Dizmar near the town of Varzaghan, according to the official IRNA news agency.

Early Monday, Iran's Red Crescent chief Pirhossein Koolivand said rescue teams had located the helicopter and were heading towards the site.

State TV reported that there were "no signs" of life among passengers "as of yet."

Local media has shared multiple images of what appeared to be the wreckage of the aircraft.

Raisi had earlier inaugurated a dam project with his Azeri counterpart, Ilham Aliyev, on the border between the two countries.

Iran's Interior Minister Ahmad Vahidi described the accident as a "hard landing due to the weather conditions".

Raisi's convoy comprised three helicopters including two that landed safely in the northwestern city of Tabriz.

Vahidi said it was "difficult to establish communication" with the third helicopter which was carrying Raisi.

Foreign Minister Hossein Amir-Abdollahian was also on board along with the governor of East Azerbaijan and the province's main imam, according to IRNA news agency.

How has Iran responded?

A total of 73 rescue teams were involved in the search, according to the Red Crescent, with IRNA saying search dogs and drones were being used.

Military personnel along with the Revolutionary Guards and the police have also been sent to the area, the army's chief-of-staff Mohammad Bagheri said.

Red Crescent rescue teams were seen on state TV on a steep slope as they attempted approaching the helicopter's location amid thick fog.

- What would happen in the event of Raisi's death? -
Under Iran's constitution, vice-president Mohmmad Mokhber should take over presidential duties if Raisi's death is officially confirmed.

Presidential elections would then be arranged within 50 days, according to the constitution.