The National Transportation Safety Board is investigating the Washington Amtrak derailment that left three people dead and several others injured. On Friday, the group released details from its initial review, but many questions remain unanswered.
Based on video recordings, the NTSB reports the crew members on board were not using any personal electronics. But seconds before the derailment, an engineer commented on the train's speed and attempted to slow down. The engineer did not, however, appear to apply the emergency brakes.
The safety board's full investigation is expected to last up to two years. Speed is likely one of the major factors in the derailment, but it's still unclear why the train was traveling so fast in a 30 mph zone.
Officials say Positive Train Control technology could've helped prevent the crash, but it wasn't activated. On Friday, the Wall Street Journal reported the sharp curve where the train derailed was originally planned to be removed, but was reportedly preserved to keep costs down.