Cuttack: A seven-year-old boy died, and his 67-year-old grandfather suffered 60% burn injuries after a fire, suspected to have been triggered by a diya before spreading to firecrackers, broke out in a residential building at Hatipakhari in Cuttack on Monday.Police said the boy, Biraj Bajoria, was rushed to SCB Medical College and Hospital, where doctors declared him brought dead. His grandfather, Ashok Bajoria, is undergoing treatment at the same hospital. The child and his grandparents were at home while his parents had been away from Cuttack.Fire broke out on the second floor of the three-storey building around 5 am. While the grandmother managed to rush out of the building, her husband and grandchild got trapped in the fire. Firefighters battled the blaze for nearly three hours before bringing it under control.City fire officer Abani Swain said fire personnel rushed to the spot after receiving information. “It took us nearly three hours to completely douse the flames. We rescued the two persons and rushed them to SCB,” Swain said.“An unnatural death (UD) case has been registered at Dargah bazaar police station,” ACP Girija Chakraborty said.An investigation is underway to ascertain the exact cause of the fire. “Preliminary findings suggest that a diya may have triggered the blaze, which subsequently spread to firecrackers and other inflammable materials inside the house,” Chakraborty added.