US-led forces say they have killed at least 15 insurgents and three civilians in fighting in southern Afghanistan.
The woman and two children died when troops raiding a suspected bomb-makers' compound came under fire in Helmand province, a US military spokesman said.
A building collapsed during the clash in Garmser district killing those trapped inside, the spokesman said.
More than 3,000 people have been killed this year as Afghan and foreign forces battle Taleban fighters in Afghanistan.
Helmand, a Taleban stronghold, has seen some of the worst of the violence.
"During one of the engagements, several militants barricaded themselves in a building on the compound and engaged coalition forces with a high volume of gun fire," a statement issued by coalition forces said.
"Coalition forces used a single grenade which killed the attacking militants. However, the building the militants were fighting from collapsed," the statement added.
The coalition said that after the clash they had recovered the bodies of a woman and two children as well as those of people they suspected were militants.
"We would like to express our heartfelt condolences to the families and loved ones of the deceased," coalition spokesman Major Chris Belcher said.
"When militants knowingly engage coalition forces with innocent people in the background, it only shows the extremists' complete disregard for innocent lives."
Qari Yousef Ahmadi, a Taleban spokesman, said that only three militants were killed during the battle and 15 other victims were civilians.
It was not possible to verify the conflicting claims independently.