* 2 killed, 116 injured
* Amtrak train diverted from main line onto side track
* Ivestigators said crash was preventable
Officials said the Amtrak's Silver Star was on its way from New York to Miami with eight crew members and about 140 passengers when the crash happened around 2:45 a.m. near Cayce.
Raleigh was one of the stops on route to Florida.
Robert Sumwalt, chairman of the National Transportation Safety Board, said at a news conference Sunday afternoon that the track the Amtrak train was on had been manually switched and "lined and locked."
It caused it to divert from the main line and onto a side track, where the freight train was parked.
"Of course key to this investigation is learning why that switch was lined that way because the expectation is the Amtrak would be cleared and would be operating straight down" the main line, Sumwalt said.
South Carolina Gov. Henry McMaster said at a news conference that a CSX freight train appeared to be on a loading track when the Amtrak train slammed into it.
"It appears that the Amtrak was on the wrong track," McMaster said at the news conference midday Sunday. "They weren't supposed to be meeting right there by the bridge, clearly. And it may be a time factor, but that's what it appears to me. But I defer to those who are experts in that and do have the correct information, but it appears that Amtrak was on the wrong track."
However, investigators they already know what could have prevented the wreck - a GPS-based system called "positive train control."
The system knows the location of all trains and the positions of all switches in an area and can prevent the kind of human error that puts two trains on the same track.
"It could have avoided this accident. That's what it's designed to do," said National Transportation Safety Board Chairman Robert Sumwalt.
Regulators have demanded the implementation of positive train control for decades, and the technology is now in place in the Northeast, but railroads that operate tracks used by Amtrak elsewhere in the U.S. have won repeated extensions from the government. The deadline for installing such equipment is now the end of 2018.
The crash happened by a rail yard about 10 miles south of Columbia, where several track spurs split off for freight cars to be unloaded.
At least 116 people were taken to hospitals, and three were admitted, hospital officials said.
According to the Lexington County coroner, the two Amtrak employees killed in the crash have been identified as 54-year-old Michael Kempf, who was the engineer and 36-year-old Michael Cella, who was the conductor.
It was the third deadly wreck involving Amtrak in less than two months.
Several people were on the train from the North Carolina area.
They were shaken up but are doing OK.
READ MORE: 'First thought was I wasn't going to make it:' NC woman said about deadly Amtrak crash
Amtrak officials worked to gather luggage and other belongings and line up buses to take passengers on to their destinations. Those who weren't hurt were taken in patrol cars to a shelter, and local businesses provided coffee and breakfast.
"We know they are shaken up quite a bit. We know this is like nothing else they have ever been through. So we wanted to get them out of the cold, get them out of the weather - get them to a warm place," sheriff's spokesman Adam Myrick said.
ABC News spoke to Alexandra Delgado who was a passenger and she told them that she got on the train in Raleigh around 9:30 p.m. Saturday. She said the train made a pit stop once after arriving in South Carolina and the accident happened about 15 minutes later.
"You never think it's gonna happen to you and I know that's cliché to say, it was just horrible," said Delgado. "People were screaming. I thought I was gonna die, I didn't think I was gonna survive that. Because I was in the cart right before the conductor, first three cars that derailed."
Amtrak released a statement on the train collision saying, "Amtrak is working to take care of everyone who was on the train, including family members of our passengers and crew."
On Wednesday, a chartered Amtrak train carrying Republican members of Congress to a strategy retreat slammed into a garbage truck at a crossing in rural Virginia, killing one person in the truck and injuring six others.
READ MORE: Train carrying GOP lawmakers strikes trash truck, killing driver
And on Dec. 18, an Amtrak train ran off the rails along a curve during its inaugural run on a route south of Tacoma, Washington, killing three people and injuring dozens. It was going nearly 80 mph, more than twice the speed limit.
Amtrak set up a passenger information line at (800) 523-9101.
The Associated Press and ABC News contributed to this story.