The gang gained entry through the backdoor of the house at Vellakadai last night, tied up the 22-year-old maidservant, forcibly took her to the kitchen and sprayed chilly powder around her body, they said.
The knife wielding gang then entered the septugenerian estate owner's room and forced him to open the almirah containing cash and jewellery and later decamped with the booty.
The estate owner and the servant maid later managed to free themselves and informed police.