902 A crime scene expert takes pictures of the scene on 7th street in Linden where 3 men tried to hijack a woman after a chase with the police that started in Robindale. 190208. Picture: Bongiwe Mchunu

Johannesburg - The number of people killed when a house collapsed at the Meyersdal Eco Estate in Alberton, south-east of Johannesburg, on Monday has risen to nine, paramedics said.

Nine people were also injured and transported to hospital, Netcare 911 spokeswoman Santi Steinmann said.

The house had collapsed while builders were busy working on it on Monday morning.

Some workers were still believed to be trapped under the rubble.

ER24 spokeswoman Luyanda Majija said two of the 27 workers were still missing.

The labour department said it had sent a team of inspectors to investigate the building collapse.

It said the inspectors would issue a preliminary report on the cause of the accident.

The estate confirmed the accident.

"Today, at approximately 10.30am, a structure at the house of one of our residents which was undergoing alterations collapsed," it said in a statement.

"Emergency services are still involved in rescue operations and the families of the affected workers have yet to be informed."

Security at the upmarket estate was tight as non-residents were questioned before they were allowed access. Some were turned away.

The estate's attorney Andrew Boerner said they were waiting for an update from emergency services.

"We ask the media to await the official statement from emergency services until such time as they have completed their rescue operation," he said outside the gates of the upmarket estate.

"We are liaising with emergency services and providing our full co-operation to them and the contractor."

The Meyersdal Eco Estate is the property from where two giraffes were removed last month.

The giraffes were being transported on the N1 highway on a truck when one of them hit its head on a bridge and died.

Last week, the Gauteng agriculture department said the estate was being investigated over whether it had the correct permits to bring in and keep giraffes. - Sapa