engineer, to amtrak. what do we know about the lawsuit? >> reporter: it would likely be the engineer. this is the second lawsuit. days ago an off duty amtrak employee alleging he was injured. he was thrown about the cabin and suffered brain trauma. >> tell us more about the investigation, what may be happening, especially over the weekend, reports an object may have hit the train with the circular pattern on the windshield. anything more to this? >> reporter: the ntsb says this investigation is wide open. they're though the rolling anything out. police are looking at the three trains hit. is there a pattern of projectiles hitting these trains? 188 hit with what the ntsb called aid fist size projectile through the front windshield. engineers call this getting rocked. they say it happens so often