The death toll in the cracker factory explosion in Odisha's Nayagarh district increased to six on Saturday, with four persons succumbing to burn injuries.Two persons were killed in the cracker factory explosion in Tantisahi of Itamati area in Nayagarh on Friday evening.While four of the injured persons succumbed to injuries on Saturday, five are battling for their lives at S.C.B. Medical College and Hospital at Cuttack, said Emergency Officer of the hospital Dr B.N. Maharana.Five persons have been admitted in surgery and plastic surgery departments and they are in critical condition, said the doctor. Chief Minister Naveen Patnaik declared Rs 2 lakh exgratia to the kin of the deceased persons.The state government would bear the medical expenses for the injured persons.At least 12 persons sustained severe burn injuries in the explosion at a cracker manufacturing unit in Nayagarh district on Friday.According to preliminary investigation, the cracker unit caught fire accidentally.Nayagarh SP K.V. Singh said investigation into the incident is being conducted by a team headed by a Sub-Divisional Police Officer (SDPO).Meanwhile, the owner of the factory has been detained for questioning.