By Ralph Ellis, Nicole Chavez and Dakin Andone, CNN

(CNN) An Amtrak passenger train was mistakenly diverted to a side track and crashed into an unmanned freight train in South Carolina, killing two Amtrak employees and injuring 116 people, federal officials said.

Engineer, conductor killed

No positive train control

CSX statement

Fuel spilled

'Nobody was panicking'

Other Amtrak accidents

CNN's Carma Hassan contributed to this report.