Ohio crews conduct a 'controlled release' of toxic chemicals from derailed train cars

A black plume rises over East Palestine, Ohio, as a result of the controlled detonation of a portion of the derailed Norfolk and Southern trains on Monday. (Gene J. Puskar/AP)

Crews in Ohio began to release hazardous chemicals from five cars of a train that derailed amid fears of a "catastrophic" explosion on Monday at the site near the Ohio-Pennsylvania border.

What officials also called a "controlled explosion" began on Monday afternoon with reports of a loud boom and large plume of black smoke seen.