A federal police officer and an official overseeing the operation said Friday that troops also secured key infrastructure as they advance to rout Daesh (ISIL) from western Mosul.
Both officials spoke on condition of anonymity in line with regulations, according to the Associated Press.
Iraq's federal police, special forces and the army are taking part in the battle, which started Sunday.
Iraqi authorities declared Mosul's eastern half "fully liberated" in January and afterward largely paused operations to prepare for the fight for the city's west.
The United Nations estimated that about 750,000 civilians are trapped in western Mosul.