A rocket fired during fighting between Afghan government and Taliban forces slammed into a house in southern Helmand province Wednesday, killing at least 15 people at a wedding party.
Police say at least 45 other people were wounded. Many of the victims were women and children.
On Thursday Afghanistan officially takes full responsibility for its own security with the end of the United States and NATO combat mission in the country.
About 12,000 U.S. and NATO personnel will remain to train, advise and assist Afghan police and the army.
The Taliban is claiming victory in the 13 year-long war with Western and Afghan troops.
Nearly 3,500 foreign troops were killed. More than 2,200 of them were Americans.
The U.S. invaded Afghanistan to overthrow the Taliban which was sheltering the al-Qaida masterminds of the September 11, 2001 terrorist attacks.