U.S.-backed Iraqi forces pushed into western Mosul after retaking the city’s airport from Islamic State, as aid agencies warned the most dangerous phase of the offensive was about to begin for hundreds of thousands of civilians.

Iraqi forces launched attacks on several fronts.

Forces of the federal police attacked Al-Tayaran district in southwest Mosul and located north of the newly-recaptured Mosul airport and engaged in fierce fighting with the militants of the Islamic State.

Gunfire echoed across the area as rockets and artillery heavily shelled the district in preparation for the advance.

Commanders expect the battle in western Mosul to be more difficult, in part because tanks and Armoured vehicles cannot pass through the narrow alleyways that crisscross ancient districts there.

Separately counter-terrorism forces clashed with Islamic State inside the southwestern district of Al-Mamoun and took full control of the Ghozlani military base.