The girls, ages 14 and 16, were cousins. They were sexually assaulted and hanged from a tree in the village of Katra Sadatganj in Uttar Pradesh state's Budaun district.
Their families accused three brothers of the deadly assault. Two of the brothers are now in custody, said police deputy inspector-general R.K.S. Rathore. Police are searching for the third brother.
Villagers are outraged both by the grisly nature of the attack and the inefficient response by police. A police constable was arrested for allegedly obstructing the investigation by siding with the suspected attackers, and delaying the case registration. Three other police officers have been suspended.
India has struggled with violence against women following high-profile attacks in recent years that included the deadly gang rape of a 23-year-old woman aboard a public bus in New Delhi in 2012. India's new prime minister, Narendra Modi, has said he intends to focus on women's safety -- a promise that women's rights groups have regarded with skepticism.