As many seven invigilators were relieved from their duties as the SSC exams began in 195 centres in Prakasam district amid tight security on Thursday. As many as 39,080 of the 39,601 students who were issued hall tickets appeared for the exam on the first day which was monitored by 59 flying squads under the supervision of Collector G.S.R.K.R.Vijaykumar.