attack against isis from the new chairman of the house intelligence committee, devin nunes it's all ahead because this is "face the nation." good morning, first the train they have asked fbi to investigate the possibility of projectile hitting amtrak 188 just before it derailed tuesday night. we begin with robert sumwalt a member of the national transportation safety board. point man on this investigation. is it possible that this thing that hit the train windshield that we now know about possible somebody shot at that train? >> we're certain lear going to be looking at that. as we pointed out we're going to to have the fbi with their technical assistance to analyze what sort of fracture pattern may be on that windshield. >> schieffer: any way that that could have been connected to the crash in this m way? >> it would be completely coincidental or causal that's what we wanted to find out. >> schieffer: somebody fired a shot at the plane? >> i've seen the fracture pattern it look like something like the size of grapefruit, if you will. it did not penetrate the entire windshield. >> schieff