Ngonze, from the Eastern Cape, started working for Gearhouse in 2016 as a regular freelance rigger.
Asked if Gearhouse was complying with safety standards, D'Alessandro said: "Gearhouse adheres to rigorous international safety standards and takes great precaution to prevent this type of incident. It has been in operation for 25 years, and to date this tragic incident has been the only fatality.
"We are taking the accident very seriously and are assisting the relevant authorities with a full investigation."
South African Roadies Association president Freddie Nyathela said people dying and exploitation of workers in the stage production industry were caused by lack of regulation.