Shiite Muslims around the world are observing Ashoura, one of the most sacred religious holy days for their sect.

 

Hundreds of thousands of people in Iraq, Iran and Lebanon are marking the day with rallies, prayers and self-flagellation.

 

Ashoura commemorates the killing of the Prophet Muhammad's grandson, the Imam Hussein, by a rival Muslim faction in Karbala in present day Iraq, in 680 A.D.

 

Hussein and his descendants are seen by Shiites as the rightful heirs to the prophet. Hussein's killing is attributed with cementing the schism between Shiite and Sunni Islam.

 

This year's somber commemoration comes amid rising tensions in the Middle East and the crisis between Iran and the U.S. in the wake of the collapsing nuclear deal between Tehran and world powers.