In that same region, intelligence officials say, 3,000 fleeing Taliban and Al Qaeda fighters have slipped over the Pakistani border.
American commanders say that Taliban and Al Qaeda fighters have dispersed into very small groups to avoid detection.
Local officials said the bombs fell near Arghandab, a district 10 miles north, where Taliban and Al Qaeda fighters are said to have been spotted.
Pockets of Taliban and Al Qaeda fighters remain.
Colonel King said some rebels were dug into caves, a tactic that Taliban and Al Qaeda fighters used in battles last year.
Initial Pentagon estimates placed the number of Taliban and Al Qaeda fighters in the valley at about 200.
It accelerated when he declared that Taliban and Al Qaeda fighters were not "prisoners of war."
They did so even though small pockets of Taliban and Al Qaeda fighters were still believed to be in the area.
American officials said that the operation last month killed hundreds of Taliban and Al Qaeda fighters on the Afghan side of the border.
She said the intelligence suggested a role by Taliban and Al Qaeda fighters, some of whom may have been operating outside of Afghanistan.