NEW DELHI: More than 24 hours after a multi-storey building collapsed in Burari here, four members of a family were pulled out alive from the debris in a late-night operation, officials said on Wednesday.

Those rescued on Tuesday night -- a couple and their two minor sons -- have been hospitalised, they said.

The family was trapped inside a pocket of space that was created after a ceiling slab of the newly constructed building fell on a cooking gas cylinder. It prevented the family members from being crushed under the debris, according to the officials.

The four-storey residential building near Oscar Public School collapsed on Monday evening, killing five people, including two minors.

"The rescue operation is still underway and is likely to continue till late Wednesday night. Multiple teams -- Delhi Police, NDRF and Delhi Fire Services -- are working round the clock," Deputy Commissioner of Police (North) Raja Banthia said.

So far 21 people have been pulled out from the rubble. While 16 of them were alive, five died, he said.