About 50 other persons had been pulled out of the rubble alive as of the time of going to press.
It was gathered that the three-storey building, which housed a school, Ohen Nursery and Primary School, and residential apartments, caved in around 10am.
At the scene of the incident, rescue operation was ongoing and the total casualty figure could not be immediately ascertained.
Rescue equipment from the Lagos State Emergency Management Agency had been deployed in the site.
Other emergency responders such as the Lagos State Ambulance Service, Lagos State Fire Service, Lagos State Building Control Agency, Federal Fire Service, National Emergency Management Agency, Nigeria Police Force, Rapid Response Squad, Nigeria Security and Civil Defence Corps, Nigeria Red Cross Society and the Lagos State Neighbourhood and Safety Corps were also present.
A resident of the area, identified simply as Iya Segun, said the building collapsed as a result of its dilapidated state, alleging that government officials responsible for inspecting and certifying buildings for habitation had always turned a blind eye after being bribed by the owners.
The son of the owner of the building, Erinoluwa Akinmoladun, said the house was under the management of a developer, whom he identified only as Mr Giwa.
He said the construction of the building was completed in 2010 by the developer, who was supposed to manage it for 10 years.
Erinoluwa, who was at the scene assisting rescue workers, added that his father had been rescued, but was not sure if all his siblings had been pulled out from the debris.
When our correspondent visited the Lagos Island General Hospital, no fewer than four pupils were brought in dead and 42 names were made available by the management as those rescued and responding to treatment.
A mother of three, identified simply as Iya Sukura, whose children attend the school, said two were in critical conditions, while her first daughter was still trapped.
A man, Mr Yekini Ayoola, said his five-year-old grandson, Fawaz, was still trapped in the rubble of the building.
The father of a survivor, Tony Ikueze, said his eight-year-old daughter, Chiamaka, had gone to the school on her own.
“She is my last born. She went on her own to the school this morning, because it is not far from where we live. I was in the bathroom and saw the building collapse when I looked through the window. At first, I thought it was a bomb blast. I thank God that my daughter survived it,” Ikueze said.
A miraculous scene occured when an 11-year-old pupil, Taofeekat Rasheed, was about to be wheeled to the morgue and her family insisted that she should be handed over to them for burial according to Islamic rites, but she suddenly showed signs of life as she opened her eyes faintly.
A cardio pulmonary resuscitation was carried out on her and she was immediately taken to the emergency room.
It was gathered that due to pressure on the Lagos Island General Hospital, many victims were being referred to the Massey Children Hospital and the Lagos University Teaching Hospital, Idi Araba.
According to the General Manager, LASEMA, Mr Adeshina Tiamiyu, the number of casualties cannot be ascertained until the rescue operation is over.
“So far, we have been able to rescue over 40 people. When we finish the rescue operation we can give an accurate number of the victims in collaboration with the medical personnel,” he stated.
The state Police Public Relations Officer, DSP Elkana Bala, said 50 pupils and eight tenants had been rescued, adding that only the medical personnel could ascertain their state of health and the number of the dead.