Policemen patrol on a street in Ahmedabad after reports of arson following the detention of Hardik Patel. (Press Trust of India photo)

My sincere appeal to the people of Gujarat to maintain peace and not to indulge in activities disrupting law & order across the state. Anandiben Patel (@anandibenpatel) August 25, 2015

Hardik Patel leaves the police station after being released.

The brief detention and release of 21-year-old Hardik Patel this evening has left Ahmedabad and nearby Surat tense, with cases of arson, allegedly by enraged supporters.Gujarat Chief Minister Anandiben Patel tweeted asking people to remain peaceful. ( 10 Developments At about 9 pm, Mr Patel was removed from the large public ground where he had during the day addressed lakhs of Patels or Patedars, the affluent and influential caste.At night, the police indiscriminately lathi-charged the crowd to force it to disperse; media persons were among those injured.Mr Patel is leading a campaign that has grown enormous in recent weeks for reservation in government jobs and colleges."In the next (Gujarat) election in 2017, the lotus (BJP symbol) will not bloom if our needs are not met," he said at the packed public ground, around which nearly 20,000 security personnel were posted.The Patels have for decades been loyal supporters of the BJP. Anandiben Patel has said they cannot be added to the list of castes entitled to quotas because Gujarat has hit the cap of 50 per cent reservation ordered by the Supreme Court.Traditionally farmers and traders, the Patels say their youth now needs employment outside family-owned enterprises and must have easier access to medical and engineering colleges.Other castes who benefit from reservation are opposed to the Patels' claim. As Mr Patel led 60,000 of his supporters today from the rally venue to present a charter of demands to local officials, clashes erupted. The police teargassed the mob.The violence signals the immense sensitivity of the issue. Mr Patel announced a hunger strike and said he would remain at the venue till the Chief Minister arrived to hear his arguments.The police detained him because he did not have permission to stay on at the public grounds after the rally.