Millions of people took to the streets of the Iranian city of Mashhad to bid a final farewell to Iran’s Supreme Leader, Ayatollah Ali Khamenei, ahead of his burial near the Imam Reza Mausoleum, Press TV reports.

An aircraft carrying the bodies of Khamenei and members of his family arrived at Shahid Hasheminejad International Airport on Thursday morning. The ceremony had to be postponed for several hours because of the enormous number of mourners in Iraq, where memorial events had earlier taken place in Najaf and Karbala.

According to the organizers, all roads leading to the Imam Reza Mausoleum were filled with people long before the procession began. Participants in the ceremony chanted religious slogans, carried red flags symbolizing remembrance of the fallen, and demanded retribution for the death of the Supreme Leader.

Because of the crowd numbering in the millions, the funeral cortege moved slowly toward the burial site. The procession was expected to take significantly longer than planned.

Ayatollah Ali Khamenei was killed on February 28 along with several members of his family as a result of a strike carried out on the first day of the 40-day US and Israeli attacks on Iran.

The multi-day farewell ceremony began in Tehran, then continued in Qom, after which mourning events were held in the Shiite holy cities of Iraq — Najaf and Karbala. The final stage of the funeral is taking place in Mashhad, where residents from different regions of Iran have arrived to bid farewell to Khamenei.