The FBI hasn't found any evidence of firearm damage to the windshield of the Amtrak train that derailed last week, killing eight people and injuring more than 200, the National Transportation Safety Board says. "The NTSB has not ruled out the possibility that another object may have struck the windshield," the NTSB says, per ABC News. "Additional updates on the investigation will be issued later this week." The probe into the crash is likely to take up to a year, the NTSB added in a tweet. Investigators want to know whether an object hitting the train may have played a role in its traveling at over 100mph—more than double its allotted speed limit—when it derailed on a curve, USA Today reports. (More Amtrak stories.)