The residential building got flattened due to the blast, they said.
The woman was killed on the spot when she tried to light the gas, police said, adding that her husband, two daughters, a grand daughter and a passer-by were seriously injured as the building collapsed under the impact of the explosion.
All the injured have been hospitalised.
Police said they suspected a gas leakage due to improper closure of knobs on the stove.
The kitchen windows were found shut and the gas might have filled the room and later igniting an explosion when the woman tried to light the stove, they said.