A roadside bomb attack in Ghazni province, south of the Afghan capital Kabul, has killed 18 people on their way to a wedding, officials say.
They said nearly all of the dead were women and children travelling in a minibus which was completely destroyed.
Taliban militants have denied any responsibility for the attack.
Afghan civilians are often hit by roadside bombs used by suspected Taliban militants to target security forces and officials.
In June, Nato handed over security for the whole of Afghanistan to Afghan forces, but some 97,000 Nato troops remain.
The attack on Sunday happened in a poor and deeply traditional Pashtun area in the east of Ghazni province, says the BBC's Afghanistan correspondent David Loyn.
Dead 'mainly women'
The minibus, tightly packed with people on their way to a wedding, was destroyed by a roadside bomb.
Fourteen women, three men and a child were killed, deputy provincial police chief Col Asadullah Ensafi was quoted as saying.
Only five of the 23 people on board, all of them women, are believed to have survived. Two remain in a critical condition.
Ander district, where the attack happened, was once described by Nato as the most dangerous and unsecured area in Ghazni province, our correspondent says.
However, a Taliban spokesman said they were not responsible, and had no operations under way in that district.
The Nato-led International Security Assistance Force Isaf currently has troops from 50 contributing nations - most of them, some 68,000, from the US - providing military back-up when needed.
By the end of 2014 all combat troops should have left. They will be replaced - if approved by the Afghan government - by a smaller force that will only train and advise.