About 184,000 pounds of toxic gas were released into the atmosphere after the 7:15 a.m. accident, The Philadelphia Inquirer reported. Everyone within a half mile of the bridge over Mantua Creek in Paulsboro was advised to evacuate while those at a greater distance were told to remain inside with doors and windows closed.
Some box cars in the 86-car train also derailed.
At least 66 people were treated at Underwood-Memorial Hospital in Woodbury, N.J., for respiratory problems, including 11 brought in by ambulance.
Paulsboro School Superintendent Frank Scambia said those students who had arrived at school were gathered in the high school gym, the South Jersey Times reported. Others were advised to remain at home or return there.
Larry Ragonese, a spokesman for the New Jersey Department of Environmental Protection, told the Inquirer that the gas dissipated quickly and three hours after the crash there was little risk of exposure.
Mantua Creek flows into the Delaware near the crash site a few miles downriver from Camden, N.J., and Philadelphia.
The same bridge collapsed in 2009, sending 16 coal cars into the creek.