From the LATimes: [www.latimes.com]

For those who don't want to read the article, here's the 10 second version: Report confirms the basic story: the truck driver mistakenly turned onto the tracks instead of 5th St. as intended. Got stuck on the tracks about 80 feet from the crossing. Student engineer did everything he could do by the book, but the collision was unavoidable once the driving error was made. So it's an accident.

Final report (as usual) will take up to a year to develop. Presumably the unusually extensive derailment will be more extensively discussed in that.

For more details: [www.ntsb.gov]