The children died during an attack on Friday against a complex near the eastern city of Gardez where a renegade Afghan commander, Mullah Jalani, was believed to have stocked weapons, said Lt. Col. Bryan Hilferty.

"The next day we discovered the bodies of two adults and six children under a collapsed," he said. "We had no indication there were noncombatants" in the compound.

Jalani was not at the site, 12 miles east of Gardez, but Hilferty said nine other people were arrested.

Hilferty said that US warplanes and troops attacked the compound in a nighttime raid, setting off secondary explosions. The bodies were discovered the following day. They appeared to have been crushed by a falling wall, he said.

He expressed regret over the death of civilians in Afghanistan, but said it was impossible to completely eliminate such incidents.

"We try very hard not to kill anyone. We would prefer to capture the terrorists rather than kill them," Hilferty said. "But in this incident, if noncombatants surround themselves with thousands of weapons and hundreds of rounds of ammunition and howitzers and mortars in a compound known to be used by a terrorist we are not completely responsible for the consequences."

Hilferty said he was not sure if the wall collapsed because of US fire or the secondary explosions caused by weapons stored at the site. There was no word of US casualties in the operation.

The news comes on the heels of a tragic US military blunder in neighboring Ghazni province on Saturday. Nine children were found dead in a field after an attack by an A-10 ground attack aircraft that was targeting a Taliban suspect.