LAGOS, Nigeria —Construction on a high-rise building that collapsed Monday in Lagos, killing at least 20 people, had been ordered halted earlier this year after inspectors found “abnormalities,” the authorities said Tuesday.
The 21-story structure was cordoned off in June after it had failed to meet structural specifications, said the Lagos State deputy governor, Obafemi Hamzat.
Workers were recently allowed to resume the job on the high-rise, Mr. Hamzat said, but on Tuesday it was no longer a construction site but a frantic rescue scene. A day earlier, the building had pancaked into a heap of concrete.
With scores still missing, government officials, security forces and volunteers descended on the area, as families crying and huddling nearby awaited news of their loved ones.
Mr. Hamzat did not specify what problems the inspectors found that had led them to order construction halted. “They saw some abnormalities,” he said, “so they shut it down for those things to be corrected.”
But the head of the Lagos State Building Control Agency, Gbolahan Oki, said the developer had used inferior material in the construction. “The materials he used, the reinforcement, are so terrible,” Mr. Oki told journalists.
The high-rise was one of three that were being put up by Fourscore Homes, a Lagos-based real estate firm. Repeated attempts to reach the company’s managing director, Femi Osibona, for comment were unsuccessful. And callers to a Fourscore phone line were told it was “no longer in service.”
The structure that collapsed was being built on Gerrard Road in the upscale Ikoyi neighborhood of Lagos, the commercial capital of Nigeria. High-rise apartments and upscale duplexes form part of the landscape.
The disaster has renewed scrutiny on a spate of building collapses in Nigeria’s rapidly expanding financial hub in recent years.
The Lagos State government said on Tuesday it was setting up an independent panel composed of professional engineering and architecture groups to look into the latest collapse. As a first step, the Lagos governor, Babajide Sanwo-Olu, announced that he had indefinitely suspended Mr. Oki, the building control agency head.
Officials voiced assurances that the inquiry would be thorough.
“We wish to state that there will be no cover-up in the search for the truth in this incident,” Gbenga Omotoso, the Lagos State commissioner for information and strategy, said in a statement.
Both Mr. Omotoso and the inspector general of police, Usman Alkali Baba, said that anyone found liable would face prosecution.
As of Tuesday, 20 deaths had been confirmed in the collapse. Nine people, all men, had been rescued, according to Lagos State officials.
Heavy rains Monday night interrupted the search-and-rescue efforts, but on Tuesday, excavators were back at work, digging through the rubble.
Femi Adesina, a special adviser to President Muhammadu Buhari, said in a statement that the president “commiserates with families who have lost loved ones.”
On Tuesday, Gerrard Road was cordoned off from vehicular traffic. But a crowd of residents, along with relatives of the missing, thronged the area and shouted their dissatisfaction with rescue efforts behind a barricade.
The authorities said a help desk would be set up at the site for people seeking information about the missing.
But some in the crowd were impatient with the rescue efforts and tried to take part in it themselves. They were stopped by security officials.
“Those people chased us out, they didn’t allow us to work,” said a man who identified himself as Samson, recounting how he had been among the first to respond when the building disintegrated.
“We entered and they chased us out again,” he said. “They are spoiling everything.”
Ben Ezeamalu reported from Lagos, and Abdi Latif Dahir from Nairobi, Kenya.Ismail Alfa contributed reporting from Maiduguri, Nigeria.