Hyderabad : The death toll in an explosion in an illegal firecracker manufacturing unit here rose to seven with five people succumbing to their wounds at a hospital Sunday.
Six of those killed were below 13 years, who were working in the unit in Shahinayatgunj.
The explosion occurred Thursday, leaving 11 children and two women with severe burns.
While one boy died Friday, another succumbed to his burns Saturday. Except for a woman, Urmila, 25, the condition of the remaining five injured remained critical.
The blast occurred in an 80 sq ft room, where house owner Narsing Rao was running the illegal unit.
Rao, whose two sisters were among the injured, was arrested by police along with his two brothers. Two other people who supplied the chemical material for making the firecrackers have also been taken into custody.
Police have registered a case against them under the Explosive Substances Act and Child Labour Act.
Rao used to pay Rs.10 to the child labourers for making 100 crackers. Children of poor and lower middle-class families were working part-time in his house after school hours. Police said Rao used to keep the main door of the house bolted when work was on.
Police suspect that the blast was caused by the pressure exerted on the crude explosive while being stuffed into crackers.
A magisterial inquiry has been ordered into the incident.