LOUISVILLE, Ky. —

We're getting a look at a potential key piece of evidence in figuring out what caused a UPS plane to catch fire and crash in Louisville.

A large cargo plane crashed during takeoff Tuesday evening from Louisville's airport.

The crash was fiery and sprawling, and ultimately led to the deaths of at least 12 people.

The NTSB, the agency investigating, said the plane's left wing caught fire and left engine detached. But why that happened is still unclear.

Black boxes on planes contain two separate devices: a cockpit voice recorder and a flight data recorder.

They are designed to withstand plane crashes and help investigators understand what happened.

The NTSB miraculously recovered the box from the UPS plane from the vast wreckage and shared this photo of it:

NTSB Co

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