A nuclear power reactor, around 65 kilometres north of New York City, has been shut down after a transformer fire.
But officials said the Indian Point plant was stable and there was no threat to local residents.
People nearby reported an explosion and smoke coming from the site.
The US Nuclear Regulatory Commission said the fire was quickly extinguished.
“These events happen occasionally. They are not unheard of and the plant responded as designed,” said NRC spokesman Eliot Brenner in a statement.
Entergy Corp, which runs the facility and is one of the largest US nuclear power operators, also said the plant was stable and there was no danger to the public or to employees.