RT - A blood-red flag, symbolizing the call to avenge the dead, has been hoisted atop the Jamkaran Mosque in the Iranian holy city of Qom. The rare sight comes as people mourn Qassem Soleimani and other officials killed by the US.

The hoisting ceremony was aired by Iranian state TV on Saturday. The blood-red flag, as well as a picture of the slain commander of the elite Quds Force, were carried to the roof of the one of the biggest and most important mosques for Shia Muslims.

The flag used in the ceremony is called the �Ya la-Tharat al-Husayn�, which dates back to the late 7th century. It was first raised after the Battle of Karbala in a call to avenge the death of Imam Husayn ibn Ali, which became one of the key events that led to the split between Shia and Sunni Islam. It has been reported that the red flag has never been unfurled atop the Jamkaran (a major holy site since the early Middle Ages) until now.

Red flags were also spotted during other events held across country in honor of the slain general. Thousands gathered in Tehran on Saturday, shouting slogans and carrying pictures of Soleimani. Some were seen setting Israeli flags on fire.

In Iraq, where Soleimani was killed in a US airstrike alongside other high-ranking Iranian and Iraqi officials, including the deputy commander of the Popular Mobilization Forces (PMF) militia, a three-day mourning period has been announced. Commemorative ceremonies there saw people stomping on and burning American flags.

A mourning house for Soleimani has been opened in Gaza, where people were also seen venting their anger at the US and Israel, as well as paying their respects to the dead.