That National Transportation Safety Board (NTSB) issued a statement on Thursday claiming that the Norfolk Southern train derailment in East Palestine, OH, was likely caused by an overheated bearing on a railcar.

The NTSB shared the following regarding the February 3 derailment:

NTSB investigators have identified and examined the rail car that initiated the derailment. Surveillance video from a residence showed what appears to be a wheel bearing in the final stage of overheat failure moments before the derailment. The wheelset from the suspected railcar has been collected as evidence for metallurgical examination. The suspected overheated wheel bearing has been collected and will be examined by engineers from the NTSB Materials Laboratory in Washington, D.C.

The NTSB noted that 11 railcars carrying hazardous materials, including vinyl chloride, were part of the derailment. A total of 38 cars were derailed.

The NTSB’s preliminary report on the East Palestine train derailment identified alerts sent by several wayside defect detectors — a railway mechanism to alert train operators of overheating bearings hot bearing detector (HBD) — to the train’s crew:

On the Fort Wayne Line of the Keystone Division, NS has equipped their rail network with HBD systems to assess the temperature conditions of wheel bearings while en route. The function of the HBD is to detect overheated bearings and provide audible real-time warnings to train crews. Train 32N passed three HBD systems on its trip before the derailment. At MP 79.9, the suspect bearing from the 23rd car had a recorded temperature of 38°F above ambient temperature. When train 32N passed the next HBD, at MP 69.01, the bearing’s recorded temperature was 103°F above ambient. The third HBD, at MP 49.81, recorded the suspect bearing’s temperature at 253°F above ambient. NS has established the following HBD alarm thresholds (above ambient temperature) and criteria for bearings:

• Between 170°F and 200°F, warm bearing (non-critical); stop and inspect
• A difference between bearings on the same axle greater than or equal to 115°F (non-critical); stop and inspect
• Greater than 200°F (critical); set out railcar

The NTSB added that it would update its finding as its investigation continues and announced a press conference scheduled later on Thursday related to its current findings.

Follow Robert Kraychik on Twitter @rkraychik.