We've learned the names of the two workers killed. A union official tells us that Chris Sheppard was a member of AFSCME and Larry Daniels was a contract worker.
On Sunday, the NTSB held a media briefing to give an update on its investigation.
"My concern coming out here, as it is with every investigation, is to find out what happened, gather the facts," said NTSB Investigator-in-Charge Jim Southworth at a Sunday news conference. "And on scene, that's all we'll do is gather the facts. We'll make the measurements, we'll open every door, we'll spread out the expertise that we'll get from the parties, and we'll look at very single part of what went on out here and make a determination as to what happened."
His final report could take as long as six months to come out.
We've learned that they'll be looking for video recordings of the cabin. There are no video recorders on the trains facing outward down the track, but there are cameras and digital recordings facing inside the cabin. This will allow investigators to see who was in the cabin at the time of the accident.
They'll also be looking into the training and safety records of individuals operating that train. NTSB investigators will also look into the certification of those who were authorized to be on the track at the time.
Southworth says they'll take as long as they need to investigate what happened and caused the deaths of two BART employees.
"Every part of the operation out here, records inspections, you name it, we'll be turning over every stone and opening every door," said Southworth.
Officials with the National Transportation Safety Board arrived in the Bay Area Sunday afternoon. They're leading the investigation into the death of a BART engineer and a contract worker struck and killed by a train on a stretch of track between Walnut Creek and Pleasant Hill Saturday afternoon.
"It was a loud bang," witness Matt More said.
The sound of impact and the disturbing scene that followed left neighbors shaken. The severity of the crash identified in this emergency call.
Central Operations: "BART emergency go ahead, Central.
Train Operator: "Central. 3963, we just struck some individuals at approximately 16.2."
"It was gruesome, it was awful, it was just sad," More said. "And it makes you think, if they weren't on strike, this would all be prevented."
Union workers walked off the job on Friday and continue to hold the line. BART officials called the accident a "tragic day in BART's history" and resisted any opportunity to make a connection between the death of their employees and previous safety issues raised by unions
"Did you have experience in operating a train?" Sal Cruz asked.
Cruz is a train controller and the Vice President of AFSCME 3993 and insists current experience can make all the difference when it comes to safely operating equipment.
"Unless you're out there every day operating those trains and that equipment, you can't replace that experience," he said.
BART officials have not said who was operating the train or the status of their certification. They say the two engineers were performing track maintenance.
"The labor issues, the negotiations are not in the forefront of our mind," said Paul Oversier with BART operations. "We just lost two people in the BART family."
BART says the train was returning to the Concord station after maintenance work when the accident happened. It will be up to the NTSB to figure out how it happened.
The investigation is expected to last anywhere between four to ten days.
Union officials held two candlelight vigils Sunday evening for the victims. One was scheduled to take place at the Walnut Creek BART Station, and a second at Lake Merritt Plaza in Oakland.