A US-led coalition air strike on an Islamic State weapons factory near the jihadists' Syria stronghold Raqa may have killed civilians, the Pentagon said Wednesday.
"Reports indicate that what appeared to be a non-military vehicle drove into the target area after the weapon was released from the aircraft," the US military's Central Command said.
"The vehicle's occupants may have perished as a result of the strike."
CENTCOM said it had referred the August 23 strike for an initial internal investigation. It did not provide additional details.
"Every report of civilian casualties, from either internal or external sources, is scrutinized regarding possible casualties and collateral damage," the statement said.
It is not uncommon for civilians to move into the blast radius of a bomb after it has been released by a drone or a plane pilot, because it can take as long as 45 seconds for the missile to hone in on a target.
Drone operators are sometimes able to change a missile's trajectory in the last seconds before impact, sending the weapon crashing into a field or deserted area.
In total, the US military has acknowledged killing 55 civilians since launching a coalition air war against the IS group in Syria and Iraq two years ago, though critics say that is a dramatic underestimate.
