The jihadist organisation's leadership ordered its fighters out of Hit, Kubaysa and Rutba, prompting thousands of civilians to take to the road to meet advancing federal forces while others enjoyed their first hours of freedom in months.
"The majority of Daesh (IS) fighters in Hit, Rutba and Kubaysa have fled through the desert to other regions," Yahya Rasool, Iraq's top security spokesman, told AFP.
Hit, around 145 kilometres west of Baghdad, was one of the main towns in Anbar province that was still held by IS.
"There is an operation to hunt them down with Iraqi aircraft," said Rasool, spokesman for the Joint Operations Command coordinating the fight against IS in Iraq.
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"Hit is surrounded by Iraqi forces from the south and north," he said.
"Thousands of families have fled the area to meet our forces."
Iraqi government forces have yet to enter Hit and no security source would immediately confirm whether any holdout IS fighters remained.
However, residents reached by AFP said no jihadists were visible today following a pullout that began on yesterday.
"Ahmed Mashaan Abdelwahed al-Batran was killed when an air raid destroyed his boat -- he was trying to cross the river with his family," he said.
"Since yesterday, the Hisba (Islamic police) has vanished from the streets. Before they withdrew, Daesh (IS) fighters booby-trapped houses, roads and government buildings," he added.
Another Hit resident said one of the first things the men did after IS pulled out was to light a cigarette.
"The young people in Hit are smoking on the street and they also changed back into their normal clothes," he said, also speaking on condition of anonymity.
Witnesses and officials said IS leaders -- many of them from the city of Mosul or foreigners -- tried to slip out of Hit by blending in with fleeing families after shaving their beards.