The deceased have been identified as Kamal (19) and his sister Geeta (23). No other members of the family were present at the time of the incident, which took place around 3.30 PM, a police official said.
Preliminary investigation has revealed that a leakage in the cylinder led to its explosion which caused the fire. It turned worse as the compressor of a refrigerator in the house also exploded, he said.
Two fire tenders were pressed into service and a rescue operation was launched but the duo could not be saved, the official said.
While Kamal died on the spot and his body was recovered after putting out the blaze, Geeta succumbed to her injuries later, the official said.
"A case of negligence causing death and other charges have been registered in connection with the incident," DCP (northeast) A K Singla said.
