The US-backed forces resumed their offensive on Baghouz last Friday, after a two-week pause to allow for the evacuation of civilians.
Surrendering jihadists were also among at least 3,000 people who have fled the pocket of IS territory since IS slowed down its offensive on Sunday, the Syrian Democratic Forces said.
A coalition official told VOA Monday that the SDF was "working diligently" to get any remaining civilians out of harms way, but admitted the number of civilians still hiding with IS fighters or being held against their will, was not known. More recently, Russian and Syrian forces have been reportedly carrying joint patrols around territory liberated from the Islamic State terror group.
"The drone killed my brother-in-law and then the mortar killed my husband", Dorothee Maquere told AFP.
The fight to clear the scattered tents and buildings that demarcate the last vestiges of the Islamic State (IS), and its self-proclaimed "caliphate", has wound on for weeks in Baghouz-a small village on the banks of the Euphrates River, close to the Syrian-Iraqi border.
"I would characterize the number of IS fighters now in SDF custody as thousands", Navy Commander Sean Robertson, a Pentagon spokesman, said in a statement, referring to the IS.
The Syrian air force mounted "a number of air strikes targeting Daesh movements in the eastern Badiya, specifically on one of the dirt roads leading to the town of al-Sukhna and southeast of the town", al-Watan said, citing a military source.
The Kurdish-led force pushed into Baghouz on Saturday.
Militants, the report noted, were escorted to al-Hol camp, with Kurds in control, located in Hasakah, a northeastern province.
After months under heavy bombardment and sometimes with very little to eat, many of those emerging from Baghouz are in poor physical and psychological health.
"The two military leaders discussed the deconfliction of coalition and Russian operations in Syria", US military spokesman Colonel Pat Ryder said.
The United Nations has said that of the estimated 13,000 civilians who evacuated Baghuz in the week preceding the SDF offensive, as many as 90 percent of them were women and children under the age of 5.
The evacuees said the bombing was intense over the past days.
The Kurdish-led SDF with the backing of the USA -led coalition has launched a crushing offensive to eliminate the IS from the eastern Euphrates River region in eastern Syria since September past year.