The collapse on Thursday of the steel structure of a bridge under construction in the Lusail City, Qatar, has caused injuries to 15 construction workers, the Peninsula has reported. The incident occurred at around 6pm as work was underway on the steel structure that was being readied for concrete. A source from the contracting firm, which was not named by the daily, said the cause of the crash could not be known immediately. "We don't know how it happened. Perhaps the steel structure did not have proper support," said the source.