Three spectators and a performer in the "Feurzabruta" acrobatic show suffered relatively minor injuries when the set fell apart during Friday night's show.
"A piece of moving stage equipment on which two artists were performing suffered a technical failure and fell slowly into an area where audience members were standing," a spokesman for the Roundhouse theater told the BBC. "The equipment was brought in for the production and was not part of the Roundhouse structure."
Witness Steven Johns told the BBC the equipment in question was suspended from the ceiling and spun around while spectators milled around below on an open floor.
"People were trying to get out from underneath," Johns said. "Fortunately, due to the efficient security service and the calm of crowd, the worst was avoided."