BAGHDAD, Dec. 31 (Xinhua) -- Hundreds of demonstrators, participating in mourning for the Hashd Shaabi members killed by U.S. attack in Iraq, gathered Tuesday outside the U.S. embassy in Baghdad's Green Zone, a security official said.

The demonstrators entered the heavily fortified Green Zone and prepared tents to hold a sit-in protest in front of the U.S. embassy, an official from the Iraqi Interior Ministry told Xinhua on condition of anonymity.