NTSB derailment investigation renews concerns about detectors, tank cars and Norfolk Southern

The National Transportation Safety Board's daylong hearing on what caused the disastrous East Palestine train derailment near the Ohio-Pennsylvania border last year gave the community, railroads and policymakers plenty to think about.

The NTSB confirmed the crash was caused by an overheating bearing on one of the rail cars, and they detailed why officials were wrong to blow open five tank cars of vinyl chloride and burn the contents.

Here are some of the agency's key findings from Tuesday's hearing: