Mayor Sovan Chatterjee, who visited the spot on Biren Roy Road (east) area, said it was apparently a case of murder from the way the bodies were discovered with deep gashes on throats.
Police said besides the bodies of septuagenarian mother Gouri Bhattacharjee and her 50-year old son, the ayah of the ailing woman and their domestic help were also found dead with throats slit in the same house.
Commissioner of Police R K Pachnanda, who inspected the place, said the matter was being investigated.
The physiotherapist of Gouri Bhattacharjee first found the front door open and alerted the neighbours.