At about 2 pm, the two men rang the doorbell at retired government employee Khairati Lal Khanna's residence in block N. They had a flower bouquet which they claimed "Mr Aggarwal" had sent for Khanna, police said.
Within seconds of opening the door, the men pushed Khanna to the ground, pinned him down and also attacked his domestic help Ram Chander when he came to his rescue.
When the two tried to raise an alarm, the duo thrashed Khanna, and Chander, the domestic help.
They were beaten up so severely that Khanna turned unconscious and Chander collapsed.
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The accused then tied their limbs with rope and allegedly decamped with around Rs 40,000 cash and jewellery worth several lakhs, police said.
It was Chander who raised an alarm after the robbers had left and called up Khanna's son, who was not at home then.
He later called up the police and both Khanna and Chander were taken to AIIMS where they are recovering, a senior official said.
Police have registered a case and a crime and forensic team too visited the spot.
CCTV footages are being examined an neighbours have been questioned. However, police have so far not been able to identify the accused.
Prima facie the accused had conducted a reccee and they knew well about their target, the official added.