Rescuers were racing against the clock to find survivors at the site in the affluent neighborhood of Ikoyi after torrential rains pounded Lagos overnight and briefly stopped the search. Large trailers were brought in to help move debris, blocking one of Ikoyi’s main roads.

Building collapses are frequent in Africa’s most populous country, where regulations are poorly enforced and construction materials often substandard.

“Currently all responders are on the ground as search and rescue is ongoing,” Lagos state official Olufemi Oke-Osanyintolu said, adding that the death toll stood at six.

Seven people have so far been rescued alive as excavators sifted rubble from the heaps of shattered concrete and twisted metal that engulfed the site where the building once stood.

Witnesses say up to 100 people were missing after the luxury residential structure crumbled, trapping workers under a pile of rubble.

President Muhammadu Buhari has called for rescue efforts to be stepped up.

Agitated families whose relatives and loved ones were missing refused to speak to media, although they could be heard accusing emergency services of lacking urgency after rescue efforts were briefly halted due to the rains.

New high-end apartments have been springing up in Ikoyi, and the collapsed building was part of three towers being built by private developer Fourscore Homes, where the cheapest unit was selling for $1.2 million.

Fourscore Homes promised in a client brochure to provide “a stress-free lifestyle, complete with a hotel flair”.

The cheapest unit was selling for $1.2 million and Fourscore Homes has said 65% of the apartments had been sold and were set to be occupied next year.

Telephone calls to numbers listed for Fourscore Homes and the main building contractor did not ring through on Tuesday.

By Chijioke Ohuocha.

(Reporting by Chijioke Ohuocha in Abuja, Libby George and Nneka Chile in Lagos, Editing by Clarence Fernandez, William Maclean).