A group of men, including at least two police officers, raped and killed two teenage sisters in rural India then hung their bodies from a mango tree.
Villagers found the girls' bodies hanging from the tree on Wednesday morning, hours after they disappeared from fields near their home in Katra village in Uttar Pradesh state, police Superintendent Atul Saxena said.
The girls, who were 14 and 15, had gone into the fields because there was no toilet in their home.
Hundreds of angry villagers stayed next to the tree for the rest of Wednesday, silently protesting alleged police inaction in the case.
Indian TV footage showed the villagers sitting under the girls' bodies as they swung in the wind, and preventing authorities from taking them down from the tree until the suspects were arrested.
Katra is about 300 kilometers southwest of the state capital, Lucknow.
Police arrested the four men later in the day and were searching for three more suspects.
Autopsies confirmed the girls had been gang-raped and strangled before being hanged, Saxena said.
The villagers accused the chief of the local police station of ignoring a complaint by the girls' father Tuesday night that the girls were missing. The station chief has since been suspended.
The family belongs to the Dalit community, also called "untouchables" and considered the lowest rung in India's age-old caste system.
India tightened its anti-rape laws last year, making gang rape punishable by the death penalty, even in cases where the victim survives.
The new laws came after the fatal gang rape of a 23-year-old woman on a moving bus in New Delhi that triggered nationwide protests.
Records show a rape is committed every 22 minutes in India, a nation of 1.2 billion people. Activists say that number is low because of an entrenched culture of tolerance for sexual violence, which leads many cases to go unreported.
Women are often pressed by family or police to stay quiet about sexual assault, experts say, and those who do report cases are often subjected to public ridicule or social stigma.
Last month, the head of Uttar Pradesh state's governing party, the regionally prominent Samajwadi Party, told an election rally that the party was opposed to the law calling for gang rapists to be executed.
"Boys will be boys," Mulayam Singh Yadav said. "They make mistakes."