"Ujjain collector Kavindra Kiyawat, a police official and few other policemen sustained minor injuries in the stone -pelting," said inspector general Madhu Kumar today.
Police had received a complaint that unidentified persons had hurled a petrol bomb at a religious place of a minority community in Begumbagh.
As the police team reached there and started inquiry, a mob which had gathered on the spot started throwing stones. Stones were also thrown from roofs of the houses in the area.
After a late night search operation, police arrested 52 persons and orders prohibiting assembly of people and movement in the areas under the jurisdiction of Kotwali, Mahakal, Kharakuan and Jiwajiganj police station were imposed.
Kumar said the situation was today tense but under control, and a large number of policemen had been deployed in the troubled areas.