— -- Thick black smoke swallowed the sky and billowed over villages south of Mosul on Wednesday, while ISIS militants torched oil wells in a scorched earth tactic as Iraqi and Kurdish forces closed in on the terrorist group's last major stronghold in Iraq.
An Iraqi-led coalition of forces have captured several villages and towns on the outskirts of Mosul this week since launching an operation to liberate Iraq’s second largest city from more than two years of ISIS rule. Dead bodies of ISIS fighters still littered the streets Wednesday as residents emerged from their homes to celebrate their newfound freedom.
ABC News’ Alex Marquardt spoke with some of the villagers about what life was like under the Islamic State's control. Their names and locations were kept anonymous due to concern for their safety.
“Half of the village was displaced because of ISIS,” one boy said in his native language, adding that he and the rest of the residents were forced to stay under ISIS rule.
One young man said he was too afraid to try to escape his village after ISIS took control in 2014. But when they tried to recruit him as a fighter, he refused.
“They make us sick,” he told ABC News. “I stayed because they have bombs in the roads and they have snipers.”
Maj. Gen. Gary Volesky, the top U.S. military ground commander in Iraq, said 13 Iraqi villages were liberated from ISIS rule on Wednesday during the operation to retake Mosul.
“The Iraqis are ahead of where I thought they would be when this operation started,” Volesky told reporters at a press conference. “They want to get there quickly. But again, it's a hard fight.”
On Monday, about 18,000 Iraqi forces, 10,000 Kurdish forces known as peshmerga and a few thousand Iraqi federal police launched the operation to free the strategic city from the Islamic State group’s grip. Roughly 100 American advisers are also involved in the mission, which is divided into two fronts -- one west of the Great Zab River and the other just north of Qayyarah.
On the fourth day of the massive military offensive, Iraqi special forces joined the fight for Mosul. Iraqi army Maj. Gen. Maan al-Saadi said the elite troops, also known as counterterrorism forces, advanced on the town of Bartella with the aid of U.S.-led coalition airstrikes and heavy artillery. The special forces are expected to lead the way into Mosul.
"God willing, we will take this town today," he said of Bartella, which ISIS seized in 2014.
Iraqi Prime Minister Haider Alabadi said Thursday the operation is advancing “more quickly” than expected.
But while the fighting intensifies, the United Nations Children’s Fund warned that an “unprecedented humanitarian crisis” looms as up to a million civilians are expected to flee Mosul in the coming days and weeks.
ABC News' Matt McGary and Luis Martinez contributed to this report. The Associated Press also contributed to this report.