Philadelphia Mayor Michael Nutter stressed that all information regarding the Amtrak train derailment was very preliminary. With secondary searches underway, both the death toll and the injury toll could rise.

Emergency crews say secondary searches underway for more passengers possibly trapped on derailed train in Philadelphia

6 critically injured, 53 others transferred to hospital and more 'walking wounded,' emergency officials report - @6abc

Amtrak derailment in Philadelphia
At least 5 people killed in Philadelphia train derailment, Mayor Michael Nutter says