
Emergency personnel work at the scene of a deadly train derailment, May 13, 2015, in Philadelphia.
Patrick Semansky/AP Photo

Rescue crews and investigators inspect the site of an Amtrak train derailment in Philadelphia, May 13, 2015.
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Emergency personnel work at the scene of a deadly train derailment, May 13, 2015, in Philadelphia.
Patrick Semansky/AP Photo

Emergency personnel walk near the scene of a deadly train wreck, May 13, 2015, in Philadelphia.
Mel Evans/AP Photo

Emergency personnel help a passenger at the scene of a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

Emergency personnel work the scene of a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

A crime scene investigator looks inside a train car after a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

Emergency personnel work the scene of a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

Emergency personnel work the scene of a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

A crime scene investigator looks inside a train car after a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

Emergency personnel work the scene of a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

Emergency personnel work the scene of a deadly train wreck, early on May 13, 2015, in Philadelphia.
Matt Slocum/AP Photo

Emergency personnel work the scene of a train wreck, May 12, 2015, in Philadelphia.
Matt Slocum/AP Photo

Emergency personnel work the scene of a train wreck, May 12, 2015, in Philadelphia.
Joseph Kaczmarek/AP Photo

An Amtrak train crashed on May 12, 2015, in Philadelphia. Train 188 was traveling from Washington to New York City.
Paul Cheung/AP Photo

A passenger is carried following an Amtrak train crash on May 12, 2015, in Philadelphia.
Paul Cheung/AP Photo

Passengers from an Amtrak train that crashed gather on May 12, 2015, in Philadelphia.
Paul Cheung/AP Photo

Emergency personnel transport a person at the scene of a train wreck, May 12, 2015, in Philadelphia.
Matt Slocum/AP Photo