The search continued Tuesday in South Africa for workers trapped in the collapse of a multi-story building under construction outside of Cape Town that left at least four people dead.

About 75 construction workers were at work when the building collapsed Monday afternoon in the town of George, located about 400 kilometers east of Cape Town.

A statement from city officials said more than 20 people were pulled from the rubble, while at least 50 construction workers remained unaccounted for.

The statement said "three teams of rescue personnel are working on three different areas within the site of the collapsed building." Several sniffer dogs have also been deployed to help in the search for any survivors.

Relatives of the missing workers are gathering at nearby city government offices to wait for news.

The cause of the collapse is under investigation.

Some information for this report came from The Associated Press, Reuters, Agence France-Presse.