Generators blamed for factory collapse A woman grieves at the site of the building collapse. A top official investigating the garment factory disaster in Bangladesh has blamed vibrations from four illegal generators for the building collapse, which killed more than 500 workers. The preliminary findings of the government inquiry, as described by lead investigator Main Uddin Khandaker, gave the clearest explanation yet for the catastrophic structural failure. "Four huge generators were set up on each of the top floors where garment factories were located, violating rules," said Mr Khandaker, a senior Home Ministry official. When these generators were started after a power cut, they created vibration and, together with the vibration of thousands of sewing machines, they triggered the collapse. Within five minutes the building caved in and sandwiched into one floor like a pack of cards. Mr Khandaker said the building, Rana Plaza, was built "for commercial use," not for factory use, and it could not withstand the vibrations because the owner used sub-standard rods, bricks and other materials to construct it. It also emerged on Friday that the engineer who warned the building could be unsafe, before it imploded on April 24, was being questioned by police after becoming the latest person to be arrested over the collapse. With bulldozers clawing at rubble on the site, the number of bodies being recovered has been increasing sharply.