According to local people, the incident was caused due to a cylinder blast in the building which left many people with burn injuries.
All injured, meanwhile, have been admitted to the Jamshedji Jeejebhoy (JJ) Hospital of the city.
Local Congress MLA Amin Patel visited the site of the mishap.
"Around 10.45 a.m to 11 a.m. this building collapsed. The building contains ground plus one floor in which 24 flats were there. I have just visited the hospital, 21 people are admitted in the hospital in which three children, less then 18 years and one man is in critical condition with 65 percent burn injury. I had a word with him as well. A total of five people have got burnt, while the remaining were in the building collapse," said Patel.
He added that the mishap occurred after a cylinder blast in the building.
"The investigation work has not started yet. But locals informed that a cylinder blast in the building and some people got burn injuries. Because of that the building also collapsed. The firemen are engaged in clearance of debris. After the investigation, we will understand the reason behind the mishap. But our main focus at present is to rescue people who are still lying under the debris and to treat them safely," said Patel.
Januddin Ahmed, a social activist, said four people were killed in the incident.
"Everything was going on forcefully (the rescue operation). Three people died on the way to hospital and one just in front of me and the remaining injured being treated in hospital. All workers were injured in the incident," said Ahmed.
More people were feared trapped in the rubble and rescue operations continued till last reports arrived in the afternoon. (ANI)