Executive George Latimer said there were three confirmed fatalities in Westchester County, including in Harrison where a car got stuck on the guardrail of the Hutchinson River Parkway.
A husband and wife were swept away by rushing water when they tried to get out of the car. The man's body was found, and police are still searching for the woman.
Latimer said more than 200 cars still abandoned on roadways.
As for Mamaroneck, it is a town that is flood prone and no stranger to rising water, but many residents say this is the worst they've ever seen.
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Mamaroneck Avenue, which is the main drag that runs towards the train station and the heart of the village, was completely covered by water Thursday morning, and crews were moving through neighborhoods and rescuing anyone trapped in their homes.
Cars were abandoned in the roads, and many reported water filling their basements and rising to the first floor. Even residents in apartment buildings were not spared, as those living the Avalon, a relatively new building, recounted.
"It happened pretty quickly, pretty fast," one resident named Alana said. "The water kept coming up and up, and before we knew it, some of us were trying to get our cars out the garage but the garage was completely flooded. And before we knew it, (the) power was out, and we were all just kind of hanging out in the common room, hoping for the best."
She lives on the first floor and said the water has never risen so high.
"We've never experienced that," she said. "We lived here our whole lives...It's the worst I've personally experienced but I know over here it can get pretty bad."
An 86-year-old woman was among those who were rescued from their homes, with mutual aid from other towns coming to help.
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Displaced residents were being taken to the high school, while others were transported to higher ground to be picked up by relatives.
Many homes were without power, and the damage was expected to take days if not weeks to clean up.
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