BISMARCK, N.D. -- Federal investigators have recovered a broken axle at the scene of an oil train derailment and fire in southeastern North Dakota but don't know whether it caused the wreck.
National Transportation Safety Board member Robert Sumwalt says investigators will be determining whether the axle caused Monday's derailment or whether it broke during the crash.
Sumwalt says investigators have found nothing wrong with the railroad track or signals along the tracks.
The NTSB said earlier that a westbound BNSF Railway train carrying grain derailed first, and a portion of it fell onto an adjacent track carrying the eastbound BNSF oil train. No one was hurt, but most residents in nearby Casselton temporarily evacuated.
Sumwalt says the investigation into the cause is still in the early stages.