(CNN) - Iraqi forces have taken another step toward wresting Mosul from ISIS.
Security forces launched a large-scale military operation Saturday to take the remaining neighborhoods under ISIS control in western Mosul, the country's Joint Operation Command said.
Soldiers are storming the Shifa neighborhood and al Jamhouri Hospital. Iraqi counterterrorism forces are advancing on the al Saha al Awla neighborhood, the command said.
Advancing toward the Old City
Police, counterterrorism and army units started storming the al-Zanjili district and headed toward the Old City, said federal police head, Lt. Gen. Ra'ed Shaker Jawdat.
The Old City is also still controlled by ISIS, and authorities hope to close in on that neighborhood with their new offensive, police said. The area will pose a challenge because of its narrow streets and ISIS' use of residents as human shields.
Police units south and north of the Old City shelled ISIS targets and headquarters in preparation to storm the neighborhood, police said Friday.
"Special units are working to evacuate the residents and helping them to get out of areas of clashes," Jawdat said Friday.
"Our forces are capable of winning the fight of the Old City and regaining the al-Nouri Mosque, and ISIS are losing control of the vital area close by al-Hadba minaret (adjacent to al-Nouri Mosque)."
Along with the Old City, other neighborhoods under ISIS control include al-Zinjili, al-Shifa, al Saha al Awla, Ras al-Kour, and Bab Sinjar.
Once Iraqi forces take back the occupied neighborhoods, the Iraqi government will announce the liberation of Mosul from ISIS, the Joint Operation Command said.
In 2014, ISIS took control of Mosul, Iraq's second-largest city. Iraqi forces in October kicked off an offensive to retake it.
Former top Iranian commander killed
Shiite and other militias in the region are also fighting ISIS, a Sunni movement.
A onetime prominent Iranian commander during the Iran-Iraq war was killed in battle near Mosul.
He is Sha'aban Nasiri, a former major-general in Iran's Islamic Revolutionary Guard Corps, Joint Operation Command spokesman Col. Mohammed Ibrahim said..
Nasiri, who had been an adviser for Popular Mobilization Units in Iraq, also known as the Hashd al-Shaabi, was killed in a roadside bombing near Baaj, west of Mosul, Ibrahim said.
Iranian media outlets reported that Nasiri was killed on the first night of the holy month of Ramadan this weekend, and buried on Saturday in the city of Karaj, near Iran's capital city Tehran.
Iran is a supporter President Bashar al-Assad's government in Syria.
Residents at risk
The fighting has caused significant displacement. The Iraqi government said more than 742,000 people have left Mosul and surrounding areas since the offensive began.
The United Nations migration agency warned Friday that the number of people fleeing western Mosul is soaring.
People lack access to clean water and medicine, and many have limited access to food, said UN Under-Secretary-General for Humanitarian Affairs Stephen O'Brien. He also expressed deep concern for the safety of civilians behind ISIS lines in western Mosul.
"Although the UN is not present in the areas where fighting is occurring, we have received very disturbing reports of families being shut inside booby-trapped homes and of children being deliberately targeted by snipers," he said.
Trump administration officials say the fight against ISIS has borne fruit. ISIS has lost 21,200 square miles (55,000 square kilometers) of territory and regained none of it, the Pentagon said recently. That's roughly the area of West Virginia or of Latvia.
Airstrikes have hit 2,600 ISIS-held oil and gas targets, resulting in the lowest revenue for the terror group since 2014, the Pentagon said. In Mosul, 980 ISIS fighters have been killed and more than 6,000 wounded.