Four people have died after a three-storey building collapsed in an upmarket part of Nigerias commercial hub Lagos. Five people have been rescued and emergency workers have been digging through rubble to find survivors. The site being built in Lagos Island is thought to have caved in during heavy rainfall. An official said the building had been sealed off earlier because work violated safety regulations. Oluwafemi Oke-Osanyintolu, head of the Lagos State Emergency Management Agency, said that despite the site being sealed off the developer continued to carry out work at nights and on weekends. The developer has not yet commented. Building collapses are common in Nigeria and construction experts blame this on a widespread disregard of regulations. Last November more than 40 people died when a partially-built block of luxury apartments crumbled in Lagos.