Mashal Gardani, or the "rolling of the torch", is an annual religious event commonly observed in Shia Muslim-majority Iran.
On the night of Tasoua, the ninth day of the Islamic lunar calendar's first month, Muharram, millions of men dressed in black take to the streets and mosques across the country. It symbolises their mourning of the death of Prophet Muhammad's grandson, Imam Hussein.
According to the tradition, Arab Shia Muslims lead the fiery event, seen here at Dowlat Abad, a district of Arab Iranians in the capital Tehran.
The commemoration takes place on the eve of Ashoura, one of the most important days for Shia Muslims.
Rituals include chanting of prayers, poetry and music. For Iranians and other Shia Muslims, they carry deep cultural and religious significance dating back many centuries.