It happened in Mansfield Twp., Burlington County on the morning of Oct. 14.
The train operator, 41-year-old Jessica Haley, was killed and nearly two dozen passengers were injured.
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The body cam video obtained exclusively by ABC News shows officers racing to get the 42 passengers off the River Line.
Glass and mangled metal are scattered through the interior of the car, along with what appears to be pieces of the tree.
On the tracks, officers separated passengers into groups depending on whether they reported any injuries.
A preliminary NTSB report said Haley had activated the brakes about 400 feet before striking the tree.
Operator killed in NJ train accident ID'd as single mother of 3; family plans to take legal action