By Joe Holden

UPPER DARBY, Pa. (CBS) — New details are emerging about the SEPTA train accident at the 69th Street Terminal in Upper Darby that left a train operator critically injured.

Officials say the operator tried at the last moment to prevent the crash, but was unable to do it in time.

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Sources tell CBS 3 the train operator is veteran employee George Mink and that he is currently in a medically-induced coma at Lankenau Medical Center.

Sources say as SEPTA El Car 57 made it into the loop behind the 69th Street Terminal during morning’s rush hour, Mink was forced to activate the train’s emergency mode – a last resort in attempts to avoid a collision.

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Mink, a 30-year SEPTA employee, was critically injured after his train plowed into the rear of Train 67, and sideswiped a third train.

Three other people were hurt, but their injuries were described as minor.

Investigators with the National Transportation Safety Board were on the ground by Tuesday evening, examining the trains, the tracks and trying to determine what went wrong.

A spokesman said nobody from the agency was available for an on-camera interview.

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SEPTA confirmed the section of track has a technology known as Automatic Train Control, which, under ideal conditions, should have made a collision next to impossible.

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That system is in place, according to a SEPTA spokesman, in the horseshoe loop of track where the train slammed into two other trains.

On the system, ten of the 13 regional rail routes have what’s known as Positive Train Control or PTC.

The system is multi-layered, with track signals, on-board train equipment and a central command center all relaying data.

Questions persist about how the collision happened if automatic train control was present and working.

Only adding to the mystery, sources say the fact Mink was able to activate the train’s emergency status suggests he didn’t have a medical emergency or lose consciousness prior to the collision.

Regular El riders say they’ll wait to pass judgement on safety.

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“Everything has a fail safe. Nothing is 100 percent, just like anything else,” said commuter Tyrone Love. “It has to work. Nothing is perfect.”