The first time I read this story I was completely shocked.
Foreshadowing begins almost immediately, as we're told the boys were collecting and piling stones. The villagers also passed the time by telling stories that evoked smiles rather than laughter.
Bobby Martin had already stuffed his pockets full of stones, and the other boys soon followed his example, selecting the smoothest and roundest stones; Bobby and Harry Jones and Dickie Delacroix-- the villagers pronounced this name "Dellacroy"--eventually made a great pile of stones in one corner of the square and guarded it against the raids of the other boys.
Soon the men began to gather. surveying their own children, speaking of planting and rain, tractors and taxes. They stood together, away from the pile of stones in the corner, and their jokes were quiet and they smiled rather than laughed.