A U.S. military investigation has concluded that airstrikes against an Islamic State checkpoint in Iraq in March probably killed four civilians, possibly including a child. 

U.S. Central Command says the checkpoint was validated as a lawful target before the strikes and that a review determined the attacks didn't violate international law.

The military says the four civilians emerged from two vehicles parked near the checkpoint after the A-10 attack plane released its weapons. 

A Central Command statement expresses regret for what it calls the unintentional loss of civilian lives. 

Several other allegations of civilian casualties linked to U.S. airstrikes in Iraq and Syria are under investigation