New Delhi, June 27 (ANI): Four metro stations in the national capital have been closed 'indefinitely', as hundreds of students said that they will protest in front of the Prime Minister's residence on Race Course Road. The stations that have been shut down are Patel Chowk, Central Secretariat, Race Course Road and Udyog Bhawan. More than 3,000 students were holding a demonstration at Civil Lines who later marched to Rajghat, against the change in pattern of the Civil Services exams -which makes CSAT compulsory for those who want to become IAS officers. UPSC aspirants had staged a protest last week outside the residence of Home Minister Rajnath Singh demanding a four-year age relaxation for appearing in the examinations of these services.