The South Jersey Times cites the Gloucester County Freeholder director Robert Damminger - a local official - who confirmed that at least one of the carriages contained vinyl chloride.
It also quote county officials as saying that an environmental clean-up firm is attempting to place booms in the waterway to contain the spill.
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The triggering of Article 50 has dominated newspaper headlines on Thursday, with many focusing on a possible threat over security by Ms May.
Twelve people have been killed and three injured after a pick-up truck and a church minibus crashed head-on in Texas.
Revenge porn offenders who attempt to magnify their targets' humiliation will face the toughest penalties under new sentencing proposals.