The wall of the kiln collapsed when 3 workers were inspecting the kiln furnace

Proximate causes:
• Inadequate tools, equipment & vehicles
• Inadequate training/knowledge transfer (Lack of understanding the process of the calcination of limestone);
• Lack of work rules/policies/ standards/procedures (lack of standard procedures for inspections);
• Inadequate work rules plan (lack of the pre-start safety review before inspection).

Source: A web-based collection and analysis of process safety incidents (https://www.sciencedirect.com/science/article/abs/pii/S0950423016302285)
Image Credit: Wikipedia