Two people were killed and 116 were injured on Sunday when an Amtrak passenger train was diverted off the main track onto a rail siding and crashed into a stationary freight train in South Carolina, CNN reported.

Amtrak Train 91 was traveling south and should have continued straight down the tracks, but the rail switch had been manually set to send the train onto the rail siding where the CSX train was parked, National Transportation Safety Board (NTSB) Chairman Robert Sumwalt said at a news conference.

"Key to that investigation is learning why that switch was lined (aligned) that way," he was quoted as having said.

The accident occurred at 2:30 a.m. Sumwalt said video from the front of the Amtrak train had been recovered and sent to Washington, where it will be inspected. That will help investigators determine what happened in the collision, including whether the train was exceeding the 59 mph speed limit.

The NTSB investigation should take 12 to 18 months, he added.

Lexington County spokesman Harrison Cahill said 116 people were injured and transported to hospitals, with injuries ranging from scratches to broken bones.

Killed were two Amtrak employees, including a train engineer and a conductor, according to CNN.

Richard Anderson, Amtrak CEO and president, told CNN that the signal system along the section of track where the crash occurred was down and the tracks were being manually controlled by CSX.

He said the CSX dispatch center directed the Amtrak train to the track where the derailment happened. Anderson said the CSX dispatch center was manually directing the Amtrak train via telephone communications.

A CSX spokesperson issued a statement on Sunday saying, "Our sincere condolences go out to the families of the two individuals who passed away following the tragic events that took place in Cayce, South Carolina, early this morning. We remain focused on providing assistance and support to those impacted by today's incident.”

"CSX hosts more passenger trains on its network than any other major railroad in the United States, and passenger rail remains one of the safest ways to travel. The National Transportation Safety Board is leading the investigation into this incident and CSX will continue working with the investigating team," added the statement.

President Donald Trump has been briefed on the accident, according to a statement from White House deputy press secretary Lindsay Walters.

"My thoughts and prayers are with all of the victims involved in this morning's train collision in South Carolina," Trump wrote in a tweet on Sunday afternoon. "Thank you to our incredible First Responders for the work they've done!"