reporter: what was supposed to be a celebration, the first run of newer, faster train service, tonight is a tragedy of twisted metal, with multiple passengers dead. oh, my god. that train is derailed. train derailment over the freeway. multiple patients. reporter: amtrak train 501 left seattle just after 6:00 a.m., heading toward portland. 86 passengers and crew on board. at 7:30, passenger chris karnes tweeting, wow, this train is fast. we are passing up traffic on i-5. minutes later, at 7:33 a.m., a lock motive and 12 cars careen off both sides of the overpass, down onto interstate 5, crushing vehicles below. amtrak 501. emergency. emergency. emergency. we are on the ground. reporter: the conductor radioing for help. hey guys, what happened? we were coming around the corner to take the bridge over i-5 there right north of nisqually and we went on the ground. is everybody okay? i m still figuring that out. we got cars everywhere and down onto the highway. as soon