Police on Sunday used water cannons and mild force to disperse protesters demanding the cancellation of the Bihar Public Service Commission exam held in Patna on December 13. Notably, nearly five lakh candidates had appeared at more than 900 centres across the state for the Combined Competitive Exams. The candidates were protesting for more than a week seeking the cancellation of the 70th Integrated Combined Competitive (Preliminary) Examination, conducted by the BPSC over allegations of a question paper leak.