The attack, which left three others wounded, occurred in Laghman province on Sunday but no militant group has so far claimed responsibility.
"Eleven people were martyred after two grenades were thrown at their house by unknown gunmen in Laghman's Baad Pakh district," the local governor's spokesman Sarhadi Zwak told AFP.
"All the victims were civilians, women and children among them," Zwak added.
One of them died of his wounds while being rushed to a hospital in neighbouring Nangarhar province, said health official Abdul Latif Qayyomi.
Twelve civilians, including eight children returning from school, were killed on Friday in a roadside bombing in the eastern province of Paktika.
The UN last week voiced alarm over the recent killing of 25 other civilians in the southern province of Helmand, most of them in US air strikes.