"The people (who) died in the NATO airstrike were civilians hunting birds with air guns in Behsood district," said Hazrat Hussain, police spokesman for Nangarhar province.
Earlier, another official had said all of the deceased were adult men.
"Our update information shows that three of them were about 12-years-old schoolchildren," Hussain said, adding that the two others were 22-year-old men.
International military forces reported launching an operation in Behsood district that killed five "enemies."
"We are aware of the rumours on civilian deaths in the operation, and we are investigating it," a NATO official said.