Investigators have now determined what caused a deadly Amtrak train derailment near the city of DuPont in Washington state.

At a meeting in Washington, D.C. Tuesday, the National Transpiration Safety Board said the December 2017 incident was the result of "human error."

The Amtrak operated train derailed during its inaugural run and “flew” off a curve before crashing onto traffic below.

Federal investigators said "sound transit's" failure to mitigate the danger of that curve and Amtrak’s inadequate training of the engineer are primarily to blame.

The NTSB said the engineer had little training on the new locomotive and missed several warning signs because he was distracted by a safety device going off in the cab.

As a result, Investigators say he never slowed down and was going more than twice the speed limit when he hit the curve.

Three people were killed in the crash and dozens of others were injured.