The building collapsed around 9 am in North Delhi's Inderlok area.
"Three people have been killed in the incident. The rescue operation is still on to bring out those who are still trapped under the debris," North Delhi Municipal Council (NDMC) mayor Yogender Chandolia told IANS.
The NDMC has provided an excavator to remove the debris in addition to the four fire tenders sent by the fire department, he added.
"Nine injured people have been taken to Bara Hindu Rao Hospital, out of them four are in critical condition," Deputy Commissioner of Police Madhur Verma told IANS.
Verma said four to five families lived in the building and around 15 people are still feared trapped under the debris.
"The Rescue operation is still underway," Verma added.