Afghan police have shot dead seven villagers near the Pakistani border after mistaking them for insurgents, police officials said.
The seven young men were collecting firewood after dark in the southern town of Spin Boldak, a common transit route for Taliban militants.
Six officers have been detained for questioning, the local commander said.
There is widespread anger over civilian deaths in Afghanistan. More than 2,400 were killed in fighting last year.
UN figures show that more than 70% were victims of Taliban attacks, but many Afghans say the deaths would not occur if foreign troops were not in the country.
President Hamid Karzai has repeatedly warned that civilian killings undermine support for his administration and the US-led military effort there.