The victims had been driving in Khost province in a large station wagon-type vehicle when the blast occurred, according to local and national officials.
"The casualties include five men, two women and three children all from one family," Talib Mangal, a spokesman for Khost's governor, told AFP.
"They were travelling to Logar province to attend a funeral."
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Provincial police spokesperson Adil Haidar confirmed the toll and incident details, while interior ministry spokesperson Nasrat Rahimi added it was a Taliban bomb placed by the side of the road.
The Taliban did not immediately comment.
Deadly violence continues to grip Afghanistan even as the US and the Taliban negotiate on-off talks aimed at reducing America's military footprint in the country in return for the insurgents ensuring an improved security situation.
Khost is southeast of Kabul and borders Pakistan.
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