Gurgaon: Unidentified persons injured a couple grievously, tied an elderly person and robbed their house of cash and gold jewellery in the wee hours here on Saturday.
The incident came to light when their maid visited the house for cleaning purposes in the morning, police said.
The assailants entered the house in sector 43 at around 4 am after breaking the iron grills, they said.
They first tied legs and hands of 75-year-old Mohan Chandra Tiwari and then injured his son Kapil and his wife Kavita criticallly when they offered resistance.
The intruders attacked Kapil, a chief engineer in Air India, and his wife with knives repeatedly, police said.
After injuring the three occupants, they robbed the house of valuables, including cash and gold jewellery, and fled, police said.
Mohan Chandra Tiwari had retired from the All India Institute of Medical Science (AIIMS).
Kapil and Kavita were admitted in a private hospital where their condition was stated to be critical.
Gurgaon Police Commissioner Alok Mittal said police had got some clues and the attackers would be arrested soon.