In this image taken from video, rescue workers and emergency teams work at the scene of a building collapse in Lagos, Nigeria, March 13, 2019. (AP)

LAGOS - Many people including children were feared trapped on Wednesday after a building containing a school collapsed in Nigeria's commercial capital Lagos, an emergency agency spokesman said, as rescue efforts began. 

Ibrahim Farinloye, spokesman for the National Emergency Management Agency's southwest region, said there was no immediate information on any casualties. 

Nigeria is frequently hit by building collapses, with weak enforcement of regulations and poor construction materials often used

"It is believed that many people including children are currently trapped in the building," he said. 

"The third floor of the building is housing a private school in the area," said Farinloye, adding that the three-story building came down at around 10 am local time. 

READ MORE: Islamic militants' resurgence threatens Nigeria polls

Workers on top of the rubble shoveled debris away as thousands of people swarmed around the rescue site -- dozens watching from rooftops and hundreds more packed into the surrounding streets, according to a Reuters reporter. 

The building was in the Ita-faji area of Lagos island, the original heart of the lagoon city before it expanded onto the mainland. 

Nigeria is frequently hit by building collapses, with weak enforcement of regulations and poor construction materials often used. In 2016, more than 100 people were killed when a church came down in southeastern Nigeria. 

ALSO READ: Gunfire heard in cities as Nigerians finally go to the polls

In Lagos that same year, a five-story building still under construction collapsed, killing at least 30 people. 

A floating school built to withstand storms and floods was also brought down in Lagos in 2016, though nobody was reported injured.