An officer in the federal police forces, which joined the battle on Thursday, said there were heavy clashes in the southeastern Palestine district, but they had made progress in two other neighborhoods, disabling a number of vehicle bombs. "We only had time to grab our clothes", he said.
The Hashd al-Shaabi forces, by themselves, have managed to liberate about 4,500 kilometers in areas near Mosul in Nineveh Province, he stated.
A senior officer in Iraq's Counter-Terrorism Service, Staff Lieutenant General Abdulghani al-Assadi said, "The second phase of liberating the left bank in Mosul was launched, and our forces began advancing toward Al-Quds neighborhood".
The Iraqi government does not release casualty figures and has restricted access to the front lines for journalists in recent weeks, but attrition rates have been high, according to soldiers and commanders.
Iraqi security forces launched the second phase of their offensive against Islamic State in the key city of Mosul on Thursday, advancing into the city with USA forces embedded closer to the front line than in the past. Coalition air support has been a major asset that has enabled Iraqi advances on the ground.
In a statement, the Combined Joint Task Force-Operation Inherent Resolve said it "takes all allegations of civilian casualties seriously" and that an investigation into the incident is being conducted.
"The enemy is now isolated inside the left (eastern) bank of Mosul", military spokesman Yahia Rassol announced on state TV.
Iraqi Prime Minister Haider al-Abadi had pledged that Mosul would be recaptured by year's end - a goal that is now out of reach, as operations in western Mosul have yet to begin.
But the self-styled Islamic State fighters have put up fierce resistance, and government forces have yet to enter the west of the city.
The operation has been slowed by concern to avoid casualties among civilians, who despite food and water shortages have mostly stayed in their homes rather than fleeing as was initially expected. According to the United Nations, over 114,000 people have been displaced from their homes.
About 200 civilians who left villages north of Mosul on Thursday, many still with the full beards required by Islamic State, were taken by Kurdish security forces to a nearby camp.