The incident happened in Sadar Bazar area of Delhi at around 7.30 a.m.
“It felt like a tremor…the building collapsed,” said an eyewitness.
The three-storeyed building was in a deplorable state and the police had informed the civic agencies seeking evacuation, sources said.
Nakki, who was in his 60s, and his sons Bunty, 35 and Salman, 28, were in the building when it collapsed.
While Salman and Bunty were taken out of the debris and taken to the Bara Hindu Rao hospital, Nakki died before he could be extricated.
Bunty later died in hospital.
Nakki had a jewellery shop in the Sadar Bazar market.
Police officials added another person living in the house had gone out when it collapsed.
Delhi fire department, disaster management team and policemen have been pressed into rescue operation, said the official.