Iran has declared five days of mourning in memory of President Ebrahim Raisi, Foreign Minister Hossein Amirabdollahian and other Iranian officials who were killed in a helicopter crash.

Many Iranians packed into mosques and squares on Monday to pray for the officials, who died on Sunday when the helicopter they were travelling in crashed in poor weather in mountains near the border with Azerbaijan.

Supreme Leader Ali Khamenei, who holds ultimate power with a final say on foreign policy and Iran’s nuclear programme, said First Vice President Mohammad Mokhber will take over as interim president.

“I announce five days of public mourning and offer my condolences to the dear people of Iran,” Khamenei said in a statement. Mokhber, like Raisi, is seen as close to Khamenei.

The bodies of Raisi, 63; Amirabdollahian, 60; and the other officials and staff were being transported to Tabriz, the capital city of Iran’s East Azerbaijan province. A memorial service will be held in the city on Tuesday, local media reported.

Iran’s state television said all government offices and private businesses in the country will be closed on Wednesday to coincide with funerals for victims.

Raisi will be buried in Mashhad, the city where he was born, on Thursday, state TV reported.

Leaders from the United States, European Union, Russia and China are among those who have conveyed their condolences to the families of the Iranian leaders.

An election to choose a new president will take place on June 28 with candidates to be registered from May 30 to June 3, Iranian state media reported.