The Uttar Pradesh Police fired water cannon on Monday at a group consisting mostly of women protesting against the gang-rape and murder of two girls in the state's Badaun district, television footage showed.
Several hundred protesters were demanding an end to violence against women at the protest outside the office of the chief minister in Lucknow. "We're not going to sleep, we'll be here, they have to stop this (violence against women)," a protester told NDTV during the demonstration.
"We're going to stay here, we're not going to give up," one middle-aged man said before the crowd was drenched by the riot police.
The two cousins, aged 14 and 12, were found hanging from a mango tree in Badaun last Wednesday morning, with subsequent tests showing they had been the victim of multiple sexual assaults. The girls had apparently gone into the fields on Tuesday night to relieve themselves because their home, like most others here, did not have toilets.
Outrage is growing over the attacks after the girls' fathers accused local police of refusing to help find those responsible because they belonged to a low caste.
India revised its laws on sex attacks in the wake of the December 2012 gang-rape of a student on a bus in New Delhi which triggered outrage, but they have done little to stem the tide of sex attacks. Mass protests erupted in Delhi and elsewhere over that attack, which unleashed seething anger at India's treatment of women.
Rights activists and politicians said the latest cases showed authorities in Uttar Pradesh were "not serious" about tackling sexual crimes.
Asked at a press conference last week about the incidence of rapes in the state, chief minister Akhilesh Yadav told a female reporter: "You haven't been harmed, have you? No, right? Great. Thank you."
The head of UP's ruling party, Mulayam Singh Yadav, who is also the chief minister's father, sparked uproar during the recent election campaign when he said rapists should not receive the death penalty because "boys will be boys".
The police have arrested five people in connection with the attacks on the girls and a CBI investigation has been ordered.