President Jacob Zuma sent his condolences on Wednesday to the families of the seven people killed when a house collapsed on them in Alberton, south of Johannesburg.
"I have learned with sadness of this horrific loss of so many lives and I wish to convey, on behalf of government and all people of South Africa, our heartfelt condolences to families, friends and relatives of the victims," he said in a statement.
"We also wish all those who were injured during this tragic incident a speedy recovery."
Seven construction workers were killed when part of the house in the Meyersdal Eco Estate collapsed on Monday. Two of the dead workers were cut in half. Eight were injured.
The National Home Builders' Registration Council said on Tuesday it was investigating the incident.
Zuma on Wednesday said a government team of inspectors and engineers had been sent to the site to investigate. He appealed to builders and project managers to comply with building and safety regulations.
The Ekurhuleni municipality said no building plans for the house had been submitted for approval.
"No plans were submitted to the city of Ekurhuleni, deeming the whole construction illegal," municipal spokesman Themba Radebe said on Tuesday.
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