Federal investigators on Thursday released a preliminary report into the derailment of a Norfolk Southern train carrying toxic chemicals in East Palestine, Ohio, earlier this month.
The report reads in part: “Surveillance video from a local residence showed what appeared to be a wheel bearing in the final stage of overheat failure moments before the derailment. The wheel bearing and affected wheelset have been collected as evidence and will be examined by the NTSB.”
National Transportation Safety Board Chairwoman Jennifer Homendy and Director of the NTSB's Office of Railroad, Pipeline and Hazardous Materials Robert J. Hall will hold a press conference Thursday afternoon at the agency's headquarters in Washington, D.C., to share their initial findings into the incident.
The agency released an investigative update last week saying that through surveillance video it identified and examined a rail car with "what appears to be a wheel bearing in the final stage of overheat failure moments before the derailment."
The wheel bearing passed three sensors prior to derailment. With each passing the temperature was higher. The third and final sensor recorded the temperature at 253 degrees. Critical audible alarms went off and instructed the crew to stop. In the process of stopping the train, automatic emergency braking kicked in and the train made a full stop. The focus will now be on car 23 and that wheel bearing.
Thirty-eight rail cars derailed in the incident, NTSB said. Eleven of those cars contained hazardous materials, five of which contained vinyl chloride, a highly volatile colorless gas produced for commercial uses.
The preliminary report does not offer a definitive cause of the derailment but will document factual evidence during the on-scene portion of the investigation.
The release of the report also coincides with Transportation Secretary Pete Buttigieg's first visit to the derailment site.
Buttigieg – who visited East Palestine Thursday – has faced criticism from Republicans for not traveling to the site sooner. The secretary defended his decision, saying on Twitter he "followed the norm of staying out of the way of the independent NTSB."
Buttigieg was joined on the trip by Amit Bose, the administrator of the Federal Railroad Administration, and Tristan Brown, the deputy administrator for the Pipeline and Hazardous Materials Safety Administration.
ABC News' Sasha Pezenik contributed to this report.