Binaya Gupta and Sharada Gupta from Madhya Pradesh died when the fire erupted in the bedroom of the first-floor flat at Buddhanagar.
By the time local residents brought the fire under control, the duo had died. The bodies were found lying in the bed and there were no signs of any struggle, The Himalayan Times reported.
The reason behind the fire is yet to be ascertained.
The couple owned a sweet shop at Shankhamul here.
The fire affected only the bedroom of the flat and did not spread to other rooms. The couple's son and two daughters were asleep in an adjacent room.
He said the cause of fire is "mysterious". "It is not even an electric short circuit. All electric wiring is intact in the room.
"We are preparing to send the bodies for postmortem. Further investigations are underway," he added.