A call about the fire at a house due to leakage in LPG cylinder was received by the Delhi Fire Service around 12.40 pm, they added.
Two fire tenders were rushed to the spot and it doused the flammes within half an hour.
Raj Kumar and his family members - Vimla, Angoothi, Laxman, Ilyas and Kalu were injured in the incident.
Bimla sustained 70 per cent burns while others 20 to 30 per cent burns, said the officer.
No injuries were reported, the police said.