BARTELLA, Iraq — Iraqi forces fought their way into two villages near Mosul on Monday as the offensive to retake the extremist-held city entered its second week and a rights group urged a probe into a suspected airstrike that hit a mosque, killing over a dozen civilians.

Iraqi special forces began shelling IS positions before dawn near Bartella, a historically Christian town to the east of Mosul that they had retaken last week. With patriotic music blaring from loudspeakers on their Humvees, they then pushed into the village of Tob Zawa, about 9 kilometers (5 ½ miles) from Mosul, amid heavy clashes.

After entering the village, they allowed more than 30 people who had been sheltering in a school to escape the fighting.

The Iraqi Federal Police, a military-style force, pushed into a small village in the Shura district south of Mosul, where they fired a large anti-aircraft gun and rocket-propelled grenades as they battled IS militants. They later appeared to have secured the village, a cluster of squat homes on a desert plain, and handed out water and other aid to civilians.

The U.S.-led coalition said it had carried out six airstrikes near Mosul on Sunday, destroying 19 fighting positions and 17 vehicles, as well as rocket and mortar launchers, artillery and tunnels.

Human Rights Watch meanwhile called for an investigation into last week’s purported airstrike in northern Iraq that struck the women’s section of a Shiite mosque in the town of Daquq.