Villagers found the girls’ bodies hanging from a tree on Wednesday morning, hours after they disappeared from fields near their home in Katra village in Uttar Pradesh state.
The girls, who were 14 and 15, had gone into the fields because there was no toilet in their home.
Hundreds of angry villagers spent the rest of Wednesday in silent protest over alleged police inaction in the case.
Indian TV channels showed video of the villagers sitting under the girls’ bodies as they swung in the wind, preventing authorities from taking them down from the tree until the suspects were arrested.
Police arrested the three men later in the day and were searching for four more suspects.
Autopsies confirmed the girls had been gang-raped and strangled before being hanged, police said.
The villagers accused the chief of the local police station of ignoring a complaint by the girls’ father on 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.
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.
I don’t get surprised anymore. Men are the most cruelest, nastiest, filthiest immoral creatures on earth. Men hate women. They can do anything against women. They can murder all women. They can make all women extinct.