The cause of the accident is a bit complex. The train had been parked for the night, on an incline. One of the five locomotives was left running to keep the air brakes powered, but it developed a small fire. The firemen powered down the locomotive when the put out the fire. At this point there is some finger-pointing; the train company blamed the firemen but the firemen said the company told them it was okay to leave.
The train should still have had manual brakes set every few cars. This isn't confirmed, but it's really sounding like the (lone) engineer may not have bothered setting them. If that's the case, he's probably going to jail...
Currently 20 confirmed dead, 50 unaccounted for - almost certainly all dead. Many victims may never be found. 40 buildings were destroyed, including the main downtown business area and many homes.
Truly unbelievable.