About 100,000 civilians are still trapped in the IS-held Old City district

Iraqi forces began storming the Islamic State (IS)-held Old City of Mosul on Sunday, an assault they hope will be the last in the eight-month campaign to seize the militants’ stronghold.

The historic district is the last still under control of the militants in the city, which used to be their capital in Iraq. It is a densely populated maze of narrow alleyways where fighting is often conducted house by house.

About 100,000 civilians remain trapped there in harrowing conditions, with little food, water and medicine and limited access to hospitals, according to the United Nations. “This will be a terrifying time for around 100,000 people still trapped in Mosul’s Old City... now at risk of getting caught up in the fierce street fighting to come,” the International Rescue Committee (IRC) said in a statement.

“This is the final chapter” in the offensive to take Mosul, said Lieutenant General Abdul Ghani al-Assadi, commander of the Counter Terrorism Service (CTS) elite units spearheading the assault.

A U.S.-led international coalition is providing air and ground support to the campaign. Several air strikes during the day hit a medical complex located just north of the Old City, alongside the western bank of the Tigris river, a Reuters TV reporter said. Armoured vehicles were heading toward the front-line north of the Old City as shelling and gunfire could be heard. The medical complex, housing the two biggest hospitals of Mosul, is still held in part by the militants who are using its buildings as sniper outposts.

Top IS leader killed

IS’s security services chief in the Old City, Kanaan Jiyad Abdullah aka Abu Amna, was killed in the morning clashes, Hisham al-Hashimi, who advises several Middle East governments on Islamic State affairs, told Reuters. The Iraqi government initially hoped to take Mosul by the end of 2016, but the campaign took longer as militants dug in the middle of civilians to fight back.

IS is also using suicide car and motorbike bombs, booby traps and sniper and mortar fire against the troops.

Vulnerable buildings

“The buildings of the old town are particularly vulnerable to collapse even if they aren't directly targeted, which could lead to even more civilian deaths than the hundreds killed so far in air strikes across the rest of the city,” the IRC said.

“We are trying to be very careful, using only light and medium weapons... to avoid casualties among civilians,” CTS commander Major General Maan Saadi told Iraqi state TV.

Hundred of civilians were killed near the frontlines in the past three weeks while fleeing the Old City, as Iraqi forces couldn’t fully secure exit corridors. “We expect thousands of families to escape from the Old City; we made all preparations to evacuate them from the frontlines,” Army colonel Salam Faraj told Reuters. IS snipers are shooting at families trying to flee on foot or by boat across the Tigris River, the UN said on Friday.