CAYCE, S.C. (AP) — The Latest on a deadly Amtrak train crash in South Carolina (all times local):

5:05 p.m.

Federal authorities say that a railway signaling system in South Carolina was down for maintenance when an Amtrak train crashed into a CSX freight locomotive on Sunday, causing the deaths of an Amtrak engineer and conductor.

National Transportation Safety Board Chairman Robert Sumwalt said Monday that the system was down so crews could install a "positive train control" system, which uses sensors and GPS to prevent trains from colliding or derailing.

Sumwalt had said earlier that if the system were up and running, it likely would have prevented the Amtrak train from colliding head-on into the freight train. In addition to the deaths, more than 100 people on the Amtrak train were injured and taken to hospitals, mostly with minor injuries.

Sumwalt says data recovered from the Amtrak train shows the engineer hit the emergency brakes three seconds before the trains collided at 50 mph (80 kph).

Sumwalt says investigators spoke to the CSX crew that left a switch in position to divert the passenger train off the main line, but he hadn't been briefed on what they said.

The chairman of the National Transportation Safety Board says an Amtrak train that crashed in South Carolina on Sunday killing two people veered into a parked freight train after the tracks were 'padlocked' in the wrong direction. (Feb. 4)

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11:10 a.m.

Officials say eight people remain hospitalized after they were injured on an Amtrak train that crashed into a parked train in South Carolina.

Palmetto Health spokeswoman Tammie Epps said two of the six patients remaining in the system's three hospitals remained in critical condition Monday morning.

Epps said in a statement that two other patients are in serious condition; one is in fair condition; and one is in good condition.

Lexington Medical Center spokeswoman Jennifer Wilson says two patients remain in that hospital in stable condition.

The conductor and engineer on the Amtrak train were killed in the wreck early Sunday near Cayce. Authorities say 116 of the other 147 passengers and crew on board the train were taken to hospitals.

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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.