Braving sweltering heat and calling for revenge, Iranians have massed for the burial of slain Supreme Leader Ali Khamenei in his hometown of Mashhad.

An Israeli strike killed Khamenei in late February, on the first day of the United States–Israel war on Iran, bringing an end to more than three-and-a-half decades of his rule.

Thousands of people filled the streets of the eastern city of Mashhad on Thursday.

The burial will be the final act in a marathon six days of funeral ceremonies that have allowed people to pay tribute in Tehran, the clerical hub of Qom, and in Iraq.

Observers have been watching closely for any sign of Khamenei’s son and successor, Mojtaba Khamenei, who has yet to make any public appearances and is said to have been injured in the same strike that killed his father.

Mashhad Governor Hassan Hosseini was quoted on Iranian state television as saying he “expects 15 million people” to attend Khamenei’s funeral.

With temperatures hitting 35 degrees Celsius (95 Fahrenheit), water sprinklers were used to keep mourners cool.

The funeral was originally set to begin on Thursday at 6am local time (02:30 GMT), but local media later cited organisers as saying it would start at 2pm (10.30 GMT) because ceremonies in Iraq had run late.

According to the official IRNA news agency, Khamenei is to be buried on Thursday evening in the Shrine of Imam Reza, Iran’s most revered place of worship.

The funeral prayer will be led by Hossein Noori Hamedani, a 101-year-old ayatollah and conservative figure in the Islamic Republic of Iran.

Khamenei will be buried with his infant granddaughter, his son-in-law, his daughter and Mojtaba Khamenei’s wife, Zahra Haddad Adel, who were all killed in the February 28 US–Israeli strikes.