Amtrak investigators are trying to figure out why a switch was turned off and set in a position that forced a train to travel off it's main track early Sunday, killing two employees and injuring more than 100 passengers.

The train was traveling from New York to Miami and derailed in South Carolina with nearly 150 on board. 

It happened around 2:35 a.m. Sunday in Cayce, South Carolina.

The Lexington County Sheriff's Department says the train was going about 59 miles per hour when it collided with a freight train parked on a side track.

At least 116 of the approximately 139 passengers and eight crew members on board were hurt.

This is the second train accident in less than a week.

A chartered Amtrak train carrying dozens of GOP lawmakers to a Republican policy retreat in West Virginia struck a garbage truck.  

Amtrak says it is cooperating fully with the National Transportation Safety Board, which is investigating why the switch sent this latest train hurtling off the track.