Black boxes have now been recovered from the scene of Tuesday night’s Amtrak derailment that killed at least six people and left more than 140 hospitalized.
The train engineer and conductor survived and are being interviewed, officials say, as rescue crews fear that there may be more casualties beneath the wreckage in Philadelphia’s Port Richmond neighborhood.
There were 243 people on board Northeast Corridor Train 188, which was traveling to New York from Washington, D.C., before all seven cars came off the tracks.
Philadelphia Mayor Michael Nutter said officials were still searching for passengers but could not say that everyone is accounted for at this point.
Teams from the National Transportation Safety Board and the Federal Railroad Administration are at the scene working to determine what caused the crash.