The National Transportation Security Board (NTSB) on Thursday issued its preliminary report on the derailment of a train carrying hazardous chemicals in East Palestine, Ohio, earlier this month, tentatively corroborating reports that a wheel bearing severely overheated ahead of the accident.

In its preliminary report, NTSB said investigators have examined the first car to derail, the 23rd overall, as well as local surveillance cameras and signal data. A nearby residence’s surveillance footage seemingly shows a wheel bearing in late-stage overheat failure immediately ahead of the accident, according to the preliminary report.

At the time of the accident, the report states, the train had passed through several hot bearing detectors (HBDs), which repeatedly tested as hotter than average and, by the third HBD, was 253 degrees above average, which meets Norfolk Southern’s criteria for “critical.” The train applied brakes at that point, but was unable to stop, according to the preliminary report.

The train, operated by Norfolk Southern Railway, derailed on Feb. 3. The 38 derailed cars included several cars containing vinyl chloride, a hazardous substance used in the production of plastics. Federal and state officials have both said drinking water in the area is safe, but both Gov. Mike DeWine (R) and Environmental Protection Agency Administrator Michael Regan have recommended residents drink bottled water.

NTSB investigators have taken possession of the wheel bearing in question as well as the affected wheel mechanism, according to the preliminary report. The investigation is ongoing and will further examine the design of the vinyl chloride tank cars and the derailment damage. It will also analyze the immediate response, in which first responders burned the five vinyl chloride tank cars to prevent a possible explosion.

In the report, NTSB emphasizes that potential environmental hazards are the purview of the EPA, which announced earlier this week that it would take over the cleanup effort and require Norfolk Southern to assume responsibility.