There are also fears that some more victims could be under the rubble.
The five persons were brought dead to Lok Nayak Jai Prakash Narain Hospital while 25 others who suffered head and limb injuries were undergoing treatment, police said.
The Municipal Corporation of Delhi ordered an inquiry into the collapse of two buildings, including a 70-year-old structure, in Chandni Mahal. It has also instructed the City Zone Deputy Commissioner to submit the preliminary report by Sep 28 and final report within three days.
The collapse also prompted Delhi government to blame MCD, saying a tragedy of this kind was "waiting to happen" in the area as the civic officials were "never bothered" to take any precautionary measures despite the dilapidated condition of the buildings.
The incident came as a stark reminder to the last November's building collapse in east Delhi's Laxmi Nagar which claimed over 70 lives.
Locals and officials said an under-construction building collapsed first, which had an impact on the multi-storey building leading to its collapse.
Construction was happening in a building adjacent to the 70-year-old building and the owner of the former structure had dug a deep foundation for constructing another floor which led to the weakening of the other building, locals claimed.
The locality where the incident took place is dotted with similar "old and dangerous" buildings. Narrow lanes leading to the disaster site has affected the pace of rescue work as people found it difficult to reach the site.