Federal investigators say the loss of electrical power from a loose wire caused a huge cargo ship to lose propulsion and steering before crashing into Baltimore’s Francis Scott Key Bridge, causing it to collapse last year and killing six construction workers. The National Transportation Safety Board voted unanimously Tuesday for the disaster's probable cause and safety recommendations during a hearing in Washington. Investigators found that a loose signal wire connection to a terminal block on the container ship called the Dali stemmed from the improper installation of a label on the wire that prevented the wire from being fully inserted.