Iranian President Ebrahim Raisi and the country’s foreign minister were found dead Monday hours after their helicopter crashed in fog, leaving the Islamic Republic without two key leaders as extraordinary tensions grip the wider Middle East.

Supreme Leader Ayatollah Ali Khamenei, who has the final say in the Shiite theocracy, quickly named a little-known vice president as caretaker and insisted the government was in control, but the deaths mark yet another blow to a country beset by pressures both at home and abroad.

Iran has offered no cause for the crash nor suggested sabotage brought down the helicopter, which fell in mountainous terrain in a sudden, intense fog.

In Tehran, Iran’s capital, businesses were open and children attended school Monday. However, there was a noticeable presence of both uniformed and plainclothes security forces downtown.

The crash comes as the Israel-Hamas war roils the region. Iran-backed Hamas led the attack that started the conflict, and Hezbollah, also supported by Tehran, has fired rockets at Israel. Last month, Iran launched its own unprecedented drone-and-missile attack on Israel.

A hard-liner who formerly led the country’s judiciary, Raisi was viewed as a protege of Khamenei. During his tenure, relations have also continued to deteriorate with the West as Iran enriched uranium closer than ever to weapons-grade levels and supplied bomb-carrying drones to Russia for its war in Ukraine.

His government has also faced years of mass protests over the ailing economy and women’s rights — making the moment that much more sensitive.

The crash killed all eight people aboard a Bell helicopter, which Iran purchased in the early 2000s, according to the state-run IRNA news agency reported. Among the dead were Iranian Foreign Minister Hossein Amirabdollahian, the governor of Iran’s East Azerbaijan province, a senior cleric from Tabriz, a Revolutionary Guard official, and three crew members, IRNA said.

Iran has flown Bell helicopters extensively since the shah’s era. But aircraft in Iran face a shortage of parts, in part because of Western sanctions, and often fly without safety checks. Against that backdrop, former Iranian Foreign Minister Mohammad Javad Zarif sought to blame the United States for the crash in an interview Monday.