BEIRUT (AP) — Syrian activists opposed to the Islamic State group say aircraft from the U.S.-led coalition have struck a boat carrying people fleeing fighting between the extremists and U.S.-backed fighters, killing at least seven civilians.

Raqqa is Being Slaughtered Silently said a boat carrying about 40 people was hit as it was crossing the Euphrates River in the northern province of Raqqa. It said the bodies of a woman and her six children were recovered.

The Sound and Picture group that traces atrocities in areas held by IS also reported the same casualty estimates.

The attack occurred in the Shuaib al-Zeker area near where U.S.-backed Syrian fighters have been on the offensive against IS under the cover of coalition airstrikes.