The robbery was reported to police on July 30 evening.
Armed robbers struck at posh Green Park area in south Delhi looting cash and valuables around Rs 50 lakh, police said on Monday.
Police said four armed robbers entered the residence of a retired engineer Vimal Nagpal at G Block in Green Park area and caught hold of 12 year old boy Dhananjay on the ground floor and took him to his mother Niyati on the first floor and started looting cash and other valuables by holding them hostage at gun point.
The robbers broke almirahs and drawers in the house in search of valuables forcing Niyati to cooperate in locating it as they roamed in the house for half an hour, said a senior police officer.
The robbery was reported to police on July 30 evening.
Police said that the robbers gained entry to the house after a servant Ranjan opened the door for them. The servant was absconding since the robbery.
A case has been registered at Safdarjung police station and teams have been formed to arrest the robbers, said the officer.
The family employed Ranjan and a maid who were present when the robbers came.
The maid Kavita was tied down while Ranjan fled before the robbers.
Role of both of them is being probed, he said.