Irbil, Iraq (CNN) Only a "couple of hundred" ISIS fighters remain in Mosul, as a US-led coalition continues to rid the terror group from Iraq's second-largest city, a coalition spokesman said Monday.

"There is still tough fighting to go," Col. Joseph Scrocca told CNN, stressing that the operation to clear ISIS from the Old City in Western Mosul has been led by Iraqi forces.

"In the Old City, just a few fighters can hold things up for some time," Scrocca said. "The ISF (Iraqi Security Forces) and coalition must be deliberate to protect the civilians that are still alive but quick enough to save them from starvation. It is a delicate balance."

Some 980 militants have been killed and more than 6,000 wounded in the push to oust ISIS, the Pentagon reported a month ago . The terror group took control of the city in 2014.

Meanwhile, about 100,000 civilians remain in the complex battlefield.

Gains for the coalition

Security forces recaptured their first neighborhood in the Old City on Monday, a statement released by Iraq's Joint Operations Command announced.

"Iraqi counter terrorism forces have liberated al-Farouq al-Awla neighborhood in the Old City in western Mosul and raised the Iraqi flag over its buildings," Nineveh operation commander, Staff Lieutenant General Abdulamir Yarallah, said in a statement.

Iraqi Security Forces launched the offensive on the historic district of the Old City in western Mosul on June 18. The area is believed to pose major challenges for ground forces because of its narrow streets and ISIS' use of human shields.

More than 700,000 people have been displaced since the offensive began, and the United Nations migration agency has warned that the number of people fleeing the city has soared in recent weeks

Historic landmarks have also been caught in the crossfire. Last week, the iconic 800-year-old al-Nuri mosque was destroyed in an explosion that Iraq and the US blamed on ISIS.

Iraq Prime Minister Haider al-Abadi described it as "an official announcement" of ISIS' defeat.