The incident took place at a three-storey building in Chak Raghunath, about 35 km from here.
"The blast took place inside a room on the top floor of the house of one Ramanand Tiwari at around 9 AM, where a tenant had stored a huge amount of explosives for making firecrackers," Deputy Superintendent of Police Brajnandan Rai said.
"Five occupants of the house injured in the explosion were rushed to a hospital where two of them, in their 30s, succumbed to injuries while the condition of the other three was stated to be critical," he said.
"Efforts were on to identify and nab the tenant and ascertain whether or not he had obtained requisite permission from concerned authorities for manufacturing firecrackers," Rai added.