Twenty years of war in Afghanistan have seen nearly 33,000 children killed or maimed, an average of one child every five hours, an aid organization has said.

"The numbers were a devastating insight into the deadly cost of war on children," said Save the Children, a London-headquartered international humanitarian organization which is said to have worked in Afghanistan since 1976 to deliver lifesaving services to children and their families, at a press release on Tuesday.

"The real number of direct child casualties of the conflict will likely be much higher than the estimated 32,945, and this number does not include children who have died due to hunger, poverty and disease in that time," the organization added.

"What remains after 20 years is a generation of children whose entire lives have been blighted by the misery and impact of war. The magnitude of human suffering of the past two decades is beyond comprehension," said Hassan Noor, Asia regional director for Save the Children.

Six children were killed on Sunday when the U.S. military carried out its latest drone strike targeting what it thought was a terrorist in a residential neighborhood of Kabul. 

"The Taliban kill us, ISIS kill us and the Americans kill us," lamented a neighbor of the victims in the wake of the strike. 

The U.S. pulled all its out forces from Afghanistan on Monday, ending the longest war in American history.