At least one person was killed and 10 injured in clashes and police firing when protests over caste-based quotas in jobs and education turned violent in the northern Indian state of Haryana, police and news reports said.
The agitation by the Jats, a farming community in northern India, began in Rohtak district six days ago and has spread to surrounding areas.
The Jats are demanding quotas in government jobs and institutions of higher education for their caste.
They have been squatting on roads and rail tracks and holding rallies in the region, bringing life to a standstill, IANS news agency reported.
Paramilitary police fired when a leader-less mob of protesters turned violent in Rohtak town and torched vehicles and damaged property, Haryana police chief YP Singhal said.
One person was killed and at least 20 people - including policemen - were injured in the clashes and firing, Rohtak district police official Saurabh Singh said.
Chief Singhal said the army had been called in to help maintain peace.
The Haryana government had decided in favour of quotas for the Jats and were looking at ways to implement them, Jawahar Yadav, a spokesman for the government, said in a televised statement.
Yadav appealed to people to maintain calm and return home.
India has an affirmative action policy favouring Dalits - also known as untouchables - other lower castes and indigenous tribal people who have been discriminated against over centuries.
The affirmative action is in the form of quotas that help the disadvantaged groups to obtain college places and jobs in government.
Over years, the government has expanded the quotas to include other communities that are economically or socially disadvantaged but have not faced as much discrimination as Dalits or tribal people.