Medics transport an injured person at a hospital after a building containing a school collapsed in Nigeria's commercial capital of Lagos, Nigeria. REUTERS/Afolabi Sotunde

Lagos - At least 20 people were killed, most of them children, when a building housing a school collapsed in Nigeria's commercial capital Lagos, a health official said on Friday.

Forty-three others were injured when the three-storey building in Lagos' Ita Faji neighbourhood, home to a school, residential apartments and shops, collapsed on Wednesday morning, Lagos state commissioner for health, Jide Idris, told dpa.

The announcement of the revised death toll comes after rescue workers called off the search for survivors on Thursday afternoon.

Initially, the National Emergency Management Agency (NEMA) had placed the number of casualties at eight.

The total number of people who had been inside the building at the time of its collapse remained unclear on Friday.

Several local newspapers reported that about 100 children had been enrolled at the building's school.

Building collapses are not uncommon in Lagos, where construction is poorly regulated. In September 2014, 115 people were killed when a guest house collapsed in the city.