"Fifteen dead including a woman and her baby while 11 rescued alive" Ibrahim Farinloye, from the National Emergency Management Agency (NEMA), told AFP in a text message after the tragedy in Lekki, Lagos.
Building collapses happen frequently in densely populated areas of the city, largely due to poor workmanship and materials. But they are rarer in wealthier districts.
Many of the buildings that fall down are not subjected to official construction approval.
In September 2014, 116 people were killed , 81 of them South Africans, when a guesthouse for followers of the popular evangelical preacher TB Joshua collapsed in a northern suburb of Lagos.
A coroner's inquest later blamed shoddy building work. Extra floors were being added to the guesthouse at the time.
Lekki, in the southeast of the city, has some of Lagos' most expensive real estate and has developed rapidly in recent years into a preferred location for wealthier Nigerians and expatriates.
The area is home to gated communities of US-style suburban homes. Prices for a detached home can reach into the millions of dollars.
It was not immediately clear what caused the collapse but it came after the first significant rainfall of the season overnight.
