Around 400-500 aspirants took out a candle march in Mukherjee Nagar area in north Delhi. They were walking towards the Bara Hindu Rao Hospital, when police tried to stop them.
The aspirants started pelting stones at the police personnel, who resorted to a baton charge, injuring many students.
The agitated students burned down two buses and a police booth in nearby Nehru Vihar area, a police official said.
At least 50 students were detained and taken to a police station, while a few injured students were taken to a hospital.
Officials said a few police personnel were also injured in the incident.
The UPSC aspirants have been protesting for the last few says demanding scrapping of the Civil Services Aptitude Test (CSAT).
Mukherjee Nagar, a residential area near Delhi University's north campus, is popular with students who pour into Delhi from other states to prepare for the civil services examination.