An investigation by the  National Transportation Safety Board (NTSB) says that inadequate manning and crewmember fatigue were to blame for a fatal tugboat accident last year.

The tugboat, named the Specialist, collided with a Tappan Zee Bridge construction site on the Hudson River near Tarrytown in March 2016. The collision caused the boat to sink--killing three crewmembers.

NTSB investigators say crewmembers on the boat had likely received less than four to five hours of uninterrupted sleep in at least three days prior to the collision.

The Specialist sank during rainy conditions, which caused strong currents to splash against the Tappan Zee Construction sites. The NTSB says this likely increased the crew's overall workload.

Those in the area say they hope these findings will prevent accidents on the water from happening again.