Derailed freight train cars sit semi-submerged in the waters of Mantua Creek after a train crash in Paulsboro, New Jersey Nov 30, 2012. A rail bridge collapsed on Friday over a creek in southern New Jersey, causing a Conrail freight train to derail and spill hazardous chemicals into the air and water, authorities said.[Photo/Agencies]

PAULSBORO, New Jersey - A railroad bridge collapsed on Friday over a creek in southern New Jersey, causing a Conrail freight train to derail and spill hazardous chemicals into the air and water, authorities said.

Seven of the 82 cars derailed, and a tanker car that fell into Mantua Creek leaked vinyl chloride into the waterway, which feeds into the Delaware River near Philadelphia, said Deborah Hersman, chairwoman of the National Transportation Safety Board.

More than 12,000 gallons (45,425 liters) of the highly toxic and flammable industrial chemical leaked from a gash in the car's side, local officials said.

Twenty-two people were examined at a nearby hospital as a precaution and were doing fine, said Larry Ragonese, a spokesman for the New Jersey Department of Environmental Protection.

Ragonese said the health danger and environmental impact were minimal.

"Initially there was a release of gas into the air that affected some nearby residents and people working right in that area," he said.

Air quality monitors in the area did not register any problem, said Lawrence Hajna, also with the DEP. "All the levels are coming in within our safety range."

Exposure to vinyl chloride can cause a burning sensation in the eyes or respiratory discomfort, the DEP said.

The accident took place at about 7 a.m. EST (1200 GMT) in Paulsboro. Area residents initially were told to stay indoors, with windows shut, and local schools were closed.

The leak was contained and no longer posed a threat, and authorities were using booms to trap the chemical in the water, Ragonese said.

At the scene, one of the freight cars was nearly vertical, nose-down and partly submerged in the creek. Other cars lay jumbled on the collapsed bridge and the embankment.

"It's part of living in Paulsboro, with refineries and trains. We accept it," said resident John Diamond, 53, who was taking photographs.

The area is thick with chemical plants, and two refineries, PBF Energy's Paulsboro and NuStar's Asphalt, are nearby.

TANK "BREACHED"

The head of the Gloucester County, New Jersey, Office of Emergency Management, Tom Butts, said the leaking tanker car in the water had a tear in it, and the tank was "breached."

About half of its contents leaked out, he said.

The tank was carrying some 25,000 gallons (94,635 liters) of the chemical, said John Burzichelli, a state assemblyman and former mayor of Paulsboro.

"When you live between two oil refineries, you have a sense that these things can happen," he said.

Locals fish and go crabbing and jet-ski in the creek in the warm months, Diamond said.

Jeff Tittel, director of the New Jersey Sierra Club, said improved safety procedures, inspection, enforcement and oversight are needed to help prevent such accidents.

"This time it was ... vinyl chloride. What if it was chlorine?" he said, referring to a chemical that is extremely dangerous if inhaled and has the potential to explode.

Also, he said there is no mechanism to alert communities to what kinds of chemicals trains are carrying through the states.

He questioned the integrity of the bridge, which is owned and operated by Conrail, since Superstorm Sandy slammed into New Jersey on October 29, causing surges in area waterways.

The cause of the accident was undetermined. The National Transportation Safety Board is investigating, and members of the agency arrived at the scene mid-afternoon.

NTSB's chairwoman said four out of the five train cars that were on the bridge when it collapsed landed in the creek, and two other cars rolled onto the embankment.

"We have requested a great deal of information from the railroad" as part of the investigation, Hersman said.

Conrail said the train consisted of two locomotives, 82 rail cars and one caboose.

"We very much regret the impact on the local community," said Conrail spokesman John Enright, who was at the scene. "We will be working very closely with federal investigators to determine the cause."

The bridge underwent extensive repairs after getting damaged in a 2009 derailment of a coal freight train, Burzichelli said.

"That bridge is very old. It's not a good day for Conrail," Burzichelli said, adding that the bridge carries three major freight trains daily.

New Jersey State Senate President Steve Sweeney, also on the scene, said a nearby homeowner reported hearing a "loud bang" from the bridge about two days ago. Burzichelli said Conrail had come out to examine it in response.

Conrail is jointly owned by rail operators CSX Corp and Norfolk Southern Corp.