India, July 6 -- Huge crowds, estimated by authorities to be in the millions, lined the streets for the funeral procession of Iran's slain supreme leader Ayatollah Ali Khamenei on Monday as the coffins of the late leader and four of his family members were carried through the capital on a large truck.

Footage shared by Iranian media from helicopters showed people stretching for kilometres from Tehran's Azadi, or Freedom, Square along the wide boulevard bearing the same name.

Among the vast crowd, many people were seen carrying red flags, which captured attention both inside and outside Iran.

Simply put, these red flags are commonly linked to martyrdom and are also regarded as a symbol of revenge in Shia Islam, according to several medi...