By Mike DeNardo

PHILADELPHIA (CBS) – The investigation is underway into a freight train derailment and chemical leak Friday in Paulsboro that sent dozens to the hospital. (see related story)

While the National Transportation Safety Board (NTSB) investigates, crews are working to offload chemicals from the four cars partly submerged in the Mantua Creek. One of those cars leaked vinyl chloride, sickening dozens.

Assemblyman John Burzichelli says the priority is removing the wreckage safely.

VIEW: Photos From The Scene

“All care and resources to do it in a safe manner will be engaged. Everyone is aware of what is at stake here. And we would prefer not to have another release of gas,” says Burzichelli.

NTSB chair Deborah Hersman says investigators will review a similar collapse and derailment on the Conrail-owned bridge three years ago.

“We are looking at those records prior to that event in 2009; at the work that was done when the bridge was repaired,” Hersman explains.

She says the NTSB is documenting evidence from the scene, but a cause for the latest derailment won’t be determined right away.

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