The incident occurred at Moulivakkam near Porur, about 20 km from Chennai.
23 people have been rescued so far and the injured are being admitted to the Ramachandra Medical College and Hospital for treatment. Around 22 people are still feared trapped under the debris of the residential building.
Chennai police Commissioner S George told NDTV, "The National Disaster Management team is conducting rescue work. Six workers who are trapped have been identified and we are trying to rescue them.The cause for the collapse is not clear but rescue operations will continue through the night."