A helicopter with Iranian President Ebrahim Raisi on board “crashed upon landing” on Sunday, state media reported, with weather conditions complicating rescue efforts.

While Raisi’s condition is unclear, state news agency IRNA said Raisi was traveling to Iran’s East Azerbaijan province — in the northwest of the country, some 375 miles from the capital of Tehran — where he was inaugurating a dam.

“President Raisi was returning from a ceremony to open a dam on Iran’s border with Azerbaijan when his helicopter crashed upon landing in Varzaqan region,” it said.

Iran’s foreign minister, Hossein Amir-Abdollahian, was also traveling in the helicopter, along with East Azerbaijan’s governor, Malik Rahmati, and Raisi’s security detail, it said. State TV IRIB said the helicopter belonged to the Iranian Red Crescent, which Iran’s interior minister Ahmad Vahidi said was part of a convoy.

Their condition remains unknown.

At least 20 rescue teams have been deployed, but harsh weather conditions and heavy fog were making it difficult for them to reach the site, state media added.

The Qiz Qalasi Dam is the third dam jointly built by Iran and neighboring Azerbaijan and took almost two decades to complete, according to state media.

While Iran flies a range of helicopters, international sanctions have made it difficult for Tehran to obtain the required parts for them. Most of the helicopters operated by the military date back to before the 1979 Islamic Revolution.

Raisi, 63, is himself under sanctions by the U.S. over his involvement in the mass execution of thousands of political prisoners in 1988 at the end of the bloody Iran-Iraq war.

He was re-elected in 2021, during an election that saw the lowest turnout in the Islamic Republic’s history. A hard-liner, Raisi formerly led the country’s judiciary and is viewed as a protégé of Iran’s Supreme Leader Ayatollah Ali Khamenei.

Under Raisi, Iran now enriches uranium at nearly weapons-grade levels and hampers international inspections. Iran has armed Russia in its war on Ukraine, as well as launched a massive drone-and-missile attack on Israel amid its war against Hamas in the Gaza Strip. It also has continued arming proxy groups in the Middle East including Yemen’s Houthi rebels and Lebanon’s Hezbollah.

This is a developing story. Check back for updates.