A grainy security-camera video has been released of the fatal Amtrak derailment Tuesday. The tape shows the train in the distance, followed by what appears to be an extraordinary explosion. At least eight people have died in the crash, and a dozen more are missing. Investigators now say the train was speeding at more than 100 miles an hour, and are focusing their investigation on 32-year-old train engineer Brandon Bostian. Bostian says he doesn’t remember the moment of the incident.