HAJ ALI, Iraq — Iraqi forces assaulted Islamic State-held villages across dusty fields south of Mosul on Tuesday, where suicide car bombers and snipers caused some two dozen casualties in a blatant reminder that militants still hold ground far from the main battlefield.

Several hundred fighters from the army and state-sanctioned Shiite militias massed in the nearby village of Haj Ali for the assault, firing mortars at Islamnic State group positions in the rural villages of Shayala Abali and Shayala Ayma, 56 miles from Iraq’s second largest city.

Columns of Humvees drove across open plain while firing heavy machine guns and kicking up thick clouds of dust. Suicide car bombers detonated charges that shook the ground a little over a half-mile away, killing at least two soldiers and wounding at least 20 who were taken to an aid station, many in shock and with shrapnel wounds.