The Latest on a deadly Amtrak train crash in South Carolina (all times local):

9:15 a.m.

Federal investigators are planning to give an update on their probe into a deadly crash between a freight train and a passenger train in South Carolina.

The National Transportation Safety Board says on Twitter that the agency will hold a meeting briefing at 4 p.m. Monday near the Columbia Metropolitan Airport.

Board Chairman Robert Sumwalt and other investigators are on the ground in Cayce (CAY-see), where an Amtrak train slammed into a freight train early Sunday, killing a conductor and an engineer. More than a hundred people were injured.

Sumwalt told reporters Sunday that a switch was in the wrong position and that a GPS-based system called "positive train control" could have prevented the crash.

The system knows the location of all trains and the positions of all switches to prevent the kind of human error that can put two trains on the same track.

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6 a.m.

Federal investigators are trying to figure out why a switch was in the wrong position sending an Amtrak train slamming into a freight train, killing a conductor and an engineer in South Carolina.

But they already know what could have prevented Sunday's wreck — a GPS-based system called "positive train control."

The system knows the location of all trains and the positions of all switches to prevent the kind of human error that can put two trains on the same track.

National Transportation Safety Board Chairman Robert Sumwalt says that system is designed to prevent crashes like the one early Sunday near Cayce (CAY-see) that killed the Amtrak train's conductor and engineer and sent 116 of the 145 other people on board the New York-to-Miami train to the hospital.