NEW YORK (CBSNewYork) — Federal investigators found “inadequate manning” and “crewmember fatigue” caused a fatal tugboat crash in the Hudson River near the Tappan Zee Bridge last year.

In the moments before the March 2016 crash, a crewmember on the 90-foot tugboat Specialist radioed to another tug to go hard left, but it was too late, WCBS 880’s Peter Haskell reported.

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The Specialist hit a construction barge and sank quickly, plunging 40 feet below the surface.

The boat was one of three tugs escorting a barge carrying a crane down the Hudson from Albany to Jersey City.

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Killed were crewmembers Paul Amon, 63, Timothy Conklin, 29, and Harry Hernandez, 56.

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The National Transportation Safety Board found the captain of the Specialist was on a sister tug at the time of the crash, but the reason is unclear.

The 12-page report released by the NTSB this week indicates crewmembers on the Specialist and its sister ship were overworked and exhausted. They had likely not had more than 4 to 5 hours of uninterrupted sleep in at least three days prior to the crash, investigators said.

The tug was also under-powered for the weather, Haskell reported.

After the crash, no workers on either tug would speak to investigators and the owner of the boat left the country, according to the report.

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The crash was the second deadly accident with a construction barge under the Tappan Zee. In July 2013, a boat operator who later confessed to drinking crashed into a dimly lit barge, killing a bride-to-be and her fiance’s best man.