Heavy airstrikes pounded the northern Deir Ezzor Province town of al-Sur, killing at least 11 civilians and wounding 35 others, according to the Syrian Observatory for Human Rights. Many of the wounded are in bad shape, and the death toll is expected to rise.

Al-Sur, like the overwhelming majority of the Deir Ezzor Province, is under ISIS control. The Syrian government controls some territory in the provincial capital, and the Kurdish YPG has seized a pair of villages in the far northwest of the province.

That the Kurdish invasion is happening not far from al-Sur, there is considerable speculation that the airstrikes were carried out by US warplanes supporting the Kurds, though as of yet there has been no claim of responsibility from anyone for the attack.

While Syria does launch some airstrikes in Deir Ezzor Province themselves, their focus has mostly been on keeping ISIS away from the airport, and it wouldn’t make much sense for them to suddenly attack al-Sur so far to the north of their sphere of influence.