Fifteen men and two women were found beheaded in Afghanistan's southern Helmand province on Monday, punishment meted out by Taliban insurgents for a mixed-sex party with music and dancing, officials said.
The bodies were found in a house near the Musa Qala district, about 75 km (46 miles) north of the provincial capital Lashkar Gah, said district governor Nimatullah, who only goes by one name.
"The victims threw a late-night dance and music party when the Taliban attacked" on Sunday night, Nimatullah told Reuters.
There were no immediate claims of responsibility.
In ultra-conservative Afghanistan, men and women do not usually mingle unless they are related, and parties involving both genders together are rare and highly secretive affairs.
For the Taliban, flirting, open displays of affection and the mixing of men and women are vehemently condemned.
According to witnesses of a major attack that killed 20 near Kabul in June, Taliban gunmen stormed a high-end hotel demanding to know where the "prostitutes and pimps" were.
The Taliban said it launched that attack on Qarga Lake because the hotel was used for "wild parties".
During their five-year reign, which was toppled by US-backed Afghan forces in 2001, sparking the present NATO-led war, the Taliban banned women from voting, most work and leaving their homes unaccompanied by their husband or a male relative.
Though those rights have been painstakingly regained, Afghanistan remains one of the worst places on earth to be a woman.
Helmand governor spokesman Daud Ahmadi said a team had been sent to the site of beheadings to investigate.