A potent rush-hour rainstorm swamped the New York metropolitan area on Friday, shutting down parts of the city's subway system, flooding streets and highways, and delaying flights into LaGuardia Airport.

Up to 5 inches (13 centimeters) of rain fell in some areas overnight, and as much as 7 inches (18 centimeters) more was expected throughout the day, New York Gov. Kathy Hochul said Friday morning.

By midday, although there was a break in the clouds, Mayor Eric Adams urged people to stay put if possible.

“It is not over, and I don't want these gaps in heavy rain to give the appearance that it is over,” he said at a news briefing. He and Hochul, both Democrats, declared states of emergency.

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No storm-related deaths or critical injuries had been reported as of midday, city officials said. But residents struggled to get around the waterlogged metropolis.

Traffic hit a standstill, with water above cars' tires, on a stretch of the FDR Drive — a major artery along the east side of Manhattan. Some drivers abandoned their vehicles.

Priscilla Fontallio said she had been stranded in her car, which was on a piece of the highway that wasn't flooded but wasn't moving, for three hours as of 11 a.m.

“Never seen anything like this in my life,” she said.

On a street in South Williamsburg, Brooklyn, workers were up to their knees in water as they tried to unclog a drain while cardboard and other debris floated by.

As the rain briefly slowed, Brooklyn residents emerged from their homes to survey the damage and begin draining the water that reached the top of many basements doors. Some people arranged milk crates and wooden boards to cross the flooded sidewalks, with water close to waist-deep in the middle of some streets.

High school student Malachi Clark stared at a flooded intersection, unsure how to proceed as he tried to get home to Brooklyn's Bedford-Stuyvesant neighborhood. He had tried to take a bus, then a train.

“When it stops the buses, you know it’s bad,” he said. (Bus service was severely disrupted citywide, according to the the Metropolitan Transportation Authority.)

A Brooklyn elementary was evacuated because its boiler was smoking, possibly because water got in, Schools Chancellor David Banks said at the news briefing. Environmental Protection Commissioner Rohit T. Aggarwala said that over 2.5 inches (6 centimeters) of rain fell in a single hour at the Brooklyn Navy Yard, overwhelming the surrounding drainage systems.

The Metropolitan Transportation Authority, which runs subway and commuter rail lines, urged residents of the nation's most populous city to stay home if they could. Virtually every subway line was at least partly suspended, rerouted or running with delays, and two of the Metro-North Railroad's three lines were suspended.

Elsewhere, photos and video posted on social media showed water pouring into subway stations and basements.

Dominic Ramunni, a meteorolgist at the National Weather Service in New York, said by phone that Friday’s rains were due to a coastal storm, with low pressure off the East Coast helping to bring in some deep moisture from the Atlantic Ocean.

Some travelers were spotted walking barefoot through flooded areas in the LaGuardia Airport.

“This will be one of the wettest days in quite some time,” he said.

Virtually every subway line was at least partly suspended, rerouted or running with delays, and two of the Metro-North Railroad's three lines were suspended.

Flights into LaGuardia were briefly halted Friday morning, and then delayed, because of water in the airport’s refueling area. Flooding also forced the closure of one of the airport’s three terminals.

Towns and cities around New York City also experienced flooding, including Hoboken, New Jersey.

Following a prior service disruption, Metro-North service has resumed in Manhattan and The Bronx. Expect residual delays.

The deluge came less than three months after a storm caused deadly floods in New York's Hudson Valley and left Vermont's capital, Montpelier, submerged. A little over two years ago, the remnants of Hurricane Ida dropped record-breaking rain on the Northeast and killed at least 13 people in New York City, most of whom were in flooded basement apartments. Overall, 50 people died from Virginia to Connecticut.

New York City officials said they received reports of six basement apartments that had flooded, but all the occupants got out safely. Hochul pleaded with residents to evacuate their homes if the water starts to rise.

“People need to take this extremely seriously,” the governor said.

Hochul warned New Yorkers on Thursday night of a forecast that called for 2-3 inches (5-7.5 centimeters) of rain, with 5 inches (13 centimeters) or more possible in some places.

“We anticipate, we warn, we prepare. But then when it hits and you have 5 inches in the last 12 hours — 3 in the last hour this morning — that’s a scale that we’re not accustomed to dealing with,” the Democrat told TV station NY1 on Friday. But she added that New Yorkers “have to get used to this” because of climate change.

As the planet warms, storms are forming in a hotter atmosphere, making extreme rainfall more frequent, according to atmospheric scientists.