The body of Iranian military commander Qassem Soleimani, who was killed in Iraq in a US military strike, was returned to Iran on Sunday, the official IRIB news agency reported.

Soleimani’s body was flown to the city of Ahvaz in southwest Iran.

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

Thousands of mourners dressed in black marched through Ahvaz, in live footage aired on state TV.

Soleimani, the architect of Tehran’s overseas clandestine and military operations as head of the Revolutionary Guards’ Quds Force, was killed on Friday in a US drone strike on his convoy at Baghdad airport.

While many Iranians have rallied in recent days to show grief over the death of Soleimani, regarded as the country’s second most powerful figure after Supreme Leader Ayatollah Ali Khamenei, others worry his death might push the country to war with a superpower.

US President Donald Trump on Saturday threatened to hit 52 Iranian sites “very hard” if Iran attacks Americans or US assets.

Khamenei promised harsh revenge and declared three days of mourning on Friday.

The body of Iranian-backed Iraqi militia leader Abu Mahdi al-Muhandis, who was killed in the attack with Soleimani, was also flown to Ahvaz, according to IRIB.

Tens of thousands of people marched in Iraq on Saturday to mourn Soleimani and al-Muhandis, chanting 'Death to America'.

On Saturday evening, a rocket fell inside Baghdad’s heavily-fortified Green Zone near the U.S. embassy, another hit the nearby Jadriya neighborhood and two more were fired at the Balad air base north of the city, but no one was killed, the Iraqi military said in a statement.

There was no immediate claim of responsibility.