A top investigator probing last week's garment factory disaster in Bangladesh on Friday blamed vibrations from four illegal generators for the collapse of the building, which killed more than 500 workers.
The preliminary findings of the government probe, 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," Khandaker, a senior home ministry official, told AFP.
"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," he said.
It also emerged Friday that an engineer who had warned that the building may be unsafe before it imploded on April 24 was being questioned by police after becoming the latest person to be arrested over the disaster.
Abdur Razzak Khan worked as the Rana Plaza owner's consultant when the owner made the illegal addition atop his five-story building, police official Ohiduzzaman said Friday.