At least 15 civilians were killed on Saturday by USA -led airstrikes, which targeted areas in the countryside of the northern province of Raqqa, the de facto capital of the Islamic State (IS) group, a monitor group reported.
The Syrian Observatory for Human Rights said at least 17 people were injured in the strike on Heneyda, and that the death toll could rise further because several of the wounded were in serious conditions.
A witness said the bombardment struck an internet cafe in Hnedia.
The coalition conducts strikes in Raqqa to support the Kurdish-led Syrian Democratic Forces (SDF), fighting against Daesh. Unverified reports estimated up to 33 people may have been killed in the strike.
While US "outrage" at civilian casualties from Syrian airstrikes is being used as a pretext for military intervention against the Syrian government, US forces continue their own airstrikes backing military operations in northeastern Syria, and are killing an increasing number of civilians in their own right.
Syrian state TV said the airstrike killed 13 including children.
Late March, media reported that at least 200 people, many of whom were civilians, were killed in recent airstrikes in Mosul.
The airbase's runways weren't hit because they're too easy to fix quickly, U.S. President Donald Trump said in an apparent response to reports that planes are taking off again from the airfield.