The massive cargo ship that brought down a major bridge in Baltimore was refloated Monday morning and slowly escorted back to port by several tugboats. The Dali, which lost power and crashed into a supporting column of the Francis Scott Key Bridge in the early hours of March 26, was expected to take about three hours to make the 2.5-mile trip from the site of the disaster to a local marine terminal, officials said. The development comes after the bodies of six construction workers killed in the incident were recovered. The victims, all of whom were Latino immigrants, were filling potholes on the roadway on the bridge at the time of the crash. A federal criminal investigation has been launched into the circumstances of the crash. Last week, the National Transportation Safety Board issued a preliminary report that found that the ship had experienced electrical issues in the hours before it even left port.