Tens of thousands of mourners have gathered in the southwestern Iranian city of Ahvaz to honor Qasem Soleimani, the commander of Iran’s Quds Force who was killed earlier in the week by a U.S. air strike while traveling in a convoy in neighboring Iraq.

State television broadcast live footage of the Sunday ceremonies showing black-clad marchers chanting and beating their chests in homage to Soleimani, whose body was returned to Iran just before dawn.

IRIB posted a video clip of a casket wrapped in an Iranian flag as it was unloaded from a plane as a military band played.

Iran has declared three days of mourning, and Soleimani’s body will be taken to the holy city of Mashad and to Tehran before his burial in his hometown of Kerman on January 7.

FILE – In this Sept. 18, 2016 photo released by the office of Iran’s supreme leader, Revolutionary Guard Gen. Qassem Soleimani, center, attends a meeting with Supreme Leader Ayatollah Ali Khamenei in Tehran.

As head of the Quds Force, the 62-year-old Soleimani helped orchestrate Tehran’s overseas clandestine and military operations.

The Quds Force, the foreign arm of Iran’s hard-line Islamic Revolutionary Guards Corps (IRGC), has been designated a foreign terrorist organization by the United States.

He was killed in a U.S. air strike, most likely by a drone, as he traveled in a convoy of Iran-backed militia members after leaving the Baghdad airport in the early morning hours of January 3 — a strike that substantially raised tensions between Washington and Tehran.

Abu Mahdi al-Muhandis, a deputy commander of the Iran-backed Hashd Shaabi militia in Iraq, was also killed in the raid.

Mourners marched earlier in Baghdad for Soleimani and others killed in the raid, while many anti-Iranian protesters celebrated the deaths at other sites in Iraq.

U.S. President Donald Trump said he ordered the strike on Soleimani, saying the Iranian commander had organized attacks on U.S. and Iraqi targets and that he was planning further terror actions.

Iran has promised “harsh revenge” for the U.S. attack on Soleimani, one of the most powerful military men in Iran.