LAGOS, March 14 (Xinhua) -- At least 12 pupils have been confirmed dead following the collapse of a three-storey building which housed a primary school in Lagos on Wednesday, according to a hospital source early Thursday.
"Some of the victims were brought in dead," a doctor told Xinhua at the Massey Children Hospital in Ita-Faji area of the Lagos Island, where some victims are being treated.
The medical officer, who wished to remain anonymous, said a pregnant woman and the proprietress of the Ohen Nursery and Primary School have also been confirmed dead.
"Some of the victims, including the pregnant woman, died after receiving treatment," he said.
While officials said the list of casualties were still being compiled and rescue operations still ongoing, several sources confirmed on Wednesday that up to nine people had died a few hours after the building collapsed.
The collapsed building housed a school, shops, and apartments.
The school had up to 172 registered pupils, and Rescuers on site said some 50 people had been rescued alive as of Wednesday night.
Lagos Island General Hospital, where most of the rescued victims were sent for treatment, has confirmed 41 people in "stable condition".
The state emergency management agency said scores of people are still trapped underneath the rubble, with no fewer than 20 school children among them.
The cause of the collapse has yet to be determined.
Governor of Lagos State Akinwunmi Ambode said a thorough investigation will be launched into the incident.
Building collapses often occur in Lagos as some property owners and developers do not adhere strictly to planning and building laws and regulations. In most cases, heavy loads are placed on the building and substandard materials are often used in the construction work.