Some 20 people from Multan, Pakistan, have been arrested for ordering the rape of a teenage girl, in revenge for a rape her brother allegedly committed.
Police said the families of the two girls are related.
Members of both had joined forces to decide what should be done.
"A jirga [village council] had ordered the rape of a 16-year-old girl as punishment, as her brother had raped a 12-year-old," police official Allah Baksh told AFP.
He said the village council was approached earlier this month by a man who said his 12-year-old sister had been raped by their cousin.
The council then ordered the complainant to rape the sister of the accused in return - which police say he did.
Pakistan's Dawn newspaper reported that the girl was forced to appear before the group and raped in front of them and her parents.
The mothers of the two girls later filed complaints at the local police station.
Medical examinations have confirmed rape in both cases.
Another officer, Ahsan Younas, told BBC Urdu that the first girl to be raped was aged between 12 and 14. The victim of the revenge rape is said to be 16 or 17.
He said police had registered a complaint against 25 people, and that the suspect accused of raping the 12-year-old was still at large.
While some reports say the group that ordered the rape was a jirga - or village council - BBC sources said it was actually formed by members of the two families.
Jirgas, a kind of council formed of local elders, often settle disputes in rural Pakistan. However, they are illegal and have been condemned for a series of controversial rulings - including ordering so-called "honour killings" and past incidents of "revenge rape".
In 2002, a jirga ordered the gang rape of 28-year-old Mukhtar Mai, whose 12-year-old brother was accused of an affair with an older woman.
Ms Mai took her rapists to court - an act of extraordinary courage in Pakistan, where sexual assault victims still face considerable stigma.
When their convictions were overturned by Pakistan's Supreme Court, she was offered many ways out of the country. However, she chose to stay in her village and start a girls' school and a women's refuge yards away from where she was raped.
Ms Mai is now a prominent women's rights activist, and her story inspired an opera, "Thumbprint", which opened in New York in 2014.