The attacks underscored the struggles faced by the Kurdish-led Syrian Democratic Forces as they try to flush the extremists out of a tent camp in eastern Syria built over a labyrinth of caves and tunnels - all that remains of a self-declared caliphate that once sprawled across large parts of Syria and neighboring Iraq.
SDF spokesman Mustafa Bali tweeted that the six killed were among dozens of civilians fleeing the IS-held area in the village of Baghouz, on the east bank of the Euphrates River. He said several other people were wounded, including three SDF fighters. The attacks took place at or near a crossing point where evacuees are searched.
Thousands of civilians have left the IS-held area in recent weeks and some fighters have surrendered. But the extremists are still putting up fierce resistance, and the SDF says it has slowed its operations out of concern for civilians and scores of prisoners held by the militants.
Friday's attacks underscore how risky the operations are, and how it can be difficult for forces to tell civilians from combatants.
An SDF official who goes by his nom de guerre, Ciyager Amed, said IS militants are still holding some 300 prisoners, both civilians and SDF fighters, adding that their fate is unknown.
The military campaign to uproot the militants from the eastern banks of the Euphrates River began in September, pushing them down toward this last corner in Baghouz, near the Iraqi border. The military operation has been halted several times since Feb. 12 as the SDF said a large number of civilians and hostages were holed up in the IS-held territory.
This week, the SDF resumed its final push before reducing pressure due to strong resistance from the extremists and the surrender of hundreds of IS fighters and family members.
Amed said there are no negotiations underway to secure the prisoners' release.
An SDF statement said hundreds of IS fighters and their families surrendered Thursday. Bali, the SDF spokesman, tweeted that a new group of IS fighters surrendered Friday, without giving further details. No one knows how many hard-core fighters, including foreigners, are still inside.
SDF commanders have stopped speculating when the battle may finally be over. Already some 25,000 people have left Baghouz, thousands more than were originally believed inside. Commanders say they don't know how many more may still be left, hiding in tunnels beneath the war-scarred village.
On Friday the situation was mostly quiet as aircraft flew over the area controlled by IS.
The capture of the last pocket still held by IS fighters in Baghouz would mark the end of a devastating four-year global campaign to end the extremist group's hold on territory in Syria and Iraq - a self-declared caliphate that at the height of the group's power in 2014 sprawled across nearly a third of both countries.
Also Friday, the Britain-based Syrian Observatory for Human Rights marked the eighth anniversary of the conflict by reporting that more than 570,000 people have been killed since Mar. 15, 2011. The conflict began with pro-democracy protests and escalated into a civil war after a fierce government crackdown and the rise of an insurgency.
Six million people have fled the country while a similar number are internally displaced.
The Observatory said it has documented 371,222 deaths by name, including 112,623 civilians. The civilians include 21,065 children and teenagers as well as 13,173 women.
The dead also include 67,000 rebels and army defectors as well as 115,000 government troops and pro-government fighters. Also killed during the conflict were some 66,000 militants, including al-Qaida-linked fighters and members of the Islamic State group.
The Observatory estimates that 105,000 people died while in government jails, mostly under torture.
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