The container ship that rammed into Baltimore’s Francis Scott Key Bridge in March lost power multiple times on both the day of the fatal accident and the day before, according to a preliminary report.

The Dali, which sails under the flag of Singapore, lost power twice on March 26 before hitting the bridge and causing it to collapse, killing six construction workers who were on the structure at the time. The first blackout was caused when electrical breakers powering most of the vessel’s equipment and lighting unexpectedly tripped, the National Transportation Safety Board said in a report Tuesday.

The crew eventually was able to restore electrical power, but then a second blackout occurred only 0.2 miles from the bridge. They regained power, but the ship lacked the propulsion needed to avoid striking the bridge, safety inspectors found.