Story highlights An estimated several thousand gallons of oil spilled into the Hudson River after fire

The oil is contained by booms in the water

No one was injured in the fire; environmental impact "not good," governor says

New York (CNN) A day after a transformer fire at New York's Indian Point nuclear plant sent thick, black smoke billowing over the facility, Gov. Andrew Cuomo warned of a new threat to the area -- gallons of oil spilling into the adjacent Hudson River.

"There is no doubt that oil was discharged into the Hudson River," Cuomo told reporters Sunday, speaking at the plant. "Exactly how much, we don't know."

The New York State Department of Environmental Conservation was on scene in Buchanan, New York, at the site of the fire and on the river Saturday night into Sunday, monitoring what Commissioner Joseph Martens called an oil sheen of up to 300 feet in diameter.

The transformer that failed ruptured during the fire, leaking oil onto the ground, Cuomo said. The oil was first caught in a holding tank but spilled over into a Hudson-bound drainage system after reaching capacity.

A spokesman for the federal Nuclear Regulatory Commission estimated the volume of oil spilled to be several thousand gallons, though Cuomo and Martens would not confirm the number.

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