MOSUL, Iraq — Iraqi special forces cleared buildings on Saturday in neighborhoods they entered in eastern Mosul a day earlier, after pushing out Islamic State militants in their drive to take back the city, as new images emerged of the barriers the extremist group mounted to obstruct the troops’ advance.

Fighting continued in the morning, with both sides firing mortars and automatic weapons on each other’s positions, while the Iraqi troops also responded with artillery. Clashes were most intense in the al-Bakr neighborhood. Sniper duels played out from rooftops in the mostly residential areas, where the majority of buildings are two stories high.

“Daesh is in the city center and we must be very careful as our forces advance,” said Maj. Gen. Sami al-Aridi of the Iraqi special forces, using the Arabic acronym for the Islamic State group.

With more densely packed neighborhoods ahead, his forces will be challenged to avoid both higher military and civilian casualties.

As he spoke, dozens of civilians in the Tahrir and Zahara districts emerged from their homes, some of them carrying white flags, and headed toward the troops to be evacuated from the battlefield.