Workers continued clearing rubble from the catastrophic collapse of a Miami footbridge on Friday as federal investigators prepared to find out what went wrong — and whether a deadly design flaw or human error was to blame.
Robert Sumwalt, chairman of the National Transportation Safety Board, said a 15-member team of experts in civil engineering, materials science and human factors would begin trying to determine what happened "so we can keep it from happening again," NBC News reported.
Officials declined to speculate on a cause after Miami-Dade Mayor Carlos Giménez raised the possibility that a "stress test" of the 950-ton bridge section was underway Thursday afternoon when the structure pancaked onto at least eight cars on the roadway below.
At least six people were killed, according to authorities.
