>> it is tuesday, december 3rd and 5:00 in the east. >> a stunning revelation in the derailment of that new york city commuter train that left four passengers killed and dozens more injured. they say the metro north train was going 82 miles an hour! >> wow. >> into a sharp curve that had a 30 miles an hour speed limit. that, folks s a bad combination. but it is still too soon, they say, to determine who or what is to blame here. a lot of questions. cnn's renee marsh is following developments for us. >> reporter: john and zoraida, we know this morning how fast that commuter train was going but still don't know why. the report shows that the train was traveling at approximately 82 miles an hour as it went into a 30-mile-an-hour curve. that is too fast for an approach that had a speed limit of 70 and way too fast for the curve's 30 miles per hour limit. deepening the mystery, the ntsb