[2] The string consisted of 47 freight cars; 25 of them were empty, but 22 of them were fully loaded, including two tank cars containing thousands of gallons of molten phenol, a toxic ingredient used in the production of many things including plastics, epoxies, nylon, numerous pharmaceutical drugs, detergents, and paints.

It causes severe chemical burns upon direct skin or eye contact and is exceedingly harmful when ingested.

[3] The engineer noticed a misaligned switch and concluded that his train, although moving slowly, would not be able to stop short of it, as the tracks were damp from rain.

However, the engineer "inadvertently failed to complete the selection process", meaning that he in effect set the train to accelerate, not to brake.

If the dynamic brakes had been properly engaged as intended, the locomotive would have used the motors against the momentum of the train as generators, causing it to slow down.

[10] Knowlton and Forson successfully coupled onto the rear car and slowed the train by applying the dynamic brakes on the chase locomotive.

Once the runaway had slowed to 12 miles per hour (19 km/h), CSX trainmaster Jon Hosfeld ran alongside the train, climbed aboard, and shut down the engine.