More than 300,000 members of India's Patel community have staged a rally in Gujarat demanding better access to jobs and education.
The rally in Ahmedabad city was addressed by Hardik Patel, a 22-year-old controversial community leader.
The rally turned violent when protesters clashed with local residents.
Patels make up 20% of the population of Gujarat, the home state of Prime Minister Narendra Modi.
The caste is economically powerful but the protesters say quotas for lower castes put them at a disadvantage.
Patels control India's thriving diamond cutting and polishing industry and are among the most prosperous businessmen and farmers in Gujarat.
But they complain that they are denied college places because of affirmative action to ensure those below them in India's complex social structure have access.
And they say they have been affected by a slowdown in small and medium industries - where many Patels are employed - in Gujarat which has led to a drying up of employment opportunities.
Led by Hardik Patel, a feisty, upcoming community leader and a businessman himself, the Patels are now demanding affirmative action and classification as Other Backward Classes (OBCs) so that they are entitled to quotas in state-run education centres and in government jobs.
OBC refers to the castes - in the middle of the Hindu caste hierarchy - who do not face so much exclusion or isolation in society but have been traditionally socially and economically disadvantaged.
Mr Patel told the audience that if people weren't given their rights, they became terrorists. He said that without quotas for Patels, the lotus would not bloom at the next state election - a reference to the symbol of Mr Modi's BJP which governs in the state as well as in Delhi.
The organisers of the rally brought in 2,500 volunteers to manage the crowds and keep peace, according to the BBC's Geeta Pandey in Ahmedabad.
"We are not against any community. We are fighting for our rights," Mr Patel told the packed audience.
"If this government does not heed our demands, the lotus will not bloom in 2017," he was quoted as saying by the NDTV news channel.
The lotus is the election symbol of the BJP, which is also running the government in Gujarat, where elections are due in 2017.
Mr Patel said the community members would call off the agitation "the day the government will indicate that it is willing to give us reservation [quotas]".
Gujarat Chief Minister Anandiben Patel has rejected their demand and urged community leaders to hold talks with the government.
"Her appeal means nothing... it is just to create confusion on the agitation ... had she been serious, she would have announced something concrete," Mr Patel was quoted as saying by the NDTV news channel.