A search and recovery effort is underway in Baltimore for six people presumed dead after the Francis Scott Key Bridge collapsed early Tuesday following a major cargo boat collision. The major shipping port remains closed, which officials say could have significant economic consequences nationwide. A team from the National Transportation Safety Board boarded the ship late Tuesday night to gather evidence for their investigation, agency Chair Jennifer Homendy told CNN on Wednesday. Officials obtained the ship’s data recorder, or black box, which Homendy said would help investigators develop a timeline of events leading up to the crash. The agency will also interview members of the ship’s crew, she said. Sources familiar with the probe say it will look into whether contaminated fuel played a role in what happened, the Wall Street Journal reported.