NEW YORK (NYTIMES) - At 9.30pm on Wednesday (Sept 1), Ms Mingma Sherpa, who lived in a basement apartment in Queens with her husband and toddler son, frantically called her upstairs neighbour for help.

"The water is coming in right now," Ms Choi Sledge, the neighbour, said, recalling Ms Sherpa's desperation. "Get out! Get to the third floor!" Ms Sledge said she screamed into the phone.

But the family did not come upstairs. Ms Sledge called them again. The call was brief. "The last thing I hear from them is, 'The water coming in from the window.' And that was it," Ms Sledge said on Thursday.

All three of her neighbours died that night - Ms Sherpa, her husband Lobsang Lama and their little boy whom people called Ang.

They drowned in a storm that pounded down the wettest hour in New York City history, according to the National Weather Service, which declared a flash flood emergency - the first ever for the city - just at the time of Ms Sherpa's phone call.

On Thursday, a day after New York City and the surrounding area were pummelled with the remnants of Hurricane Ida, an onslaught with a destructive power of shocking proportions, the region took stock of the mounting dead: As at late afternoon, at least 15 people had been found dead in New York state, at least 23 people had been killed in New Jersey, four were found dead in Pennsylvania and one person died in Connecticut.

Families and friends of the dead reeled as they relived the split seconds when the water took the people they loved. It was painfully sunny on Thursday, following the chaos of a storm that had swept in at about 9pm the night before, washing through homes, swallowing up vehicles and sucking down lives.

Some victims were killed by collapsing structures, while others were overcome by onrushing water. In South Plainfield, New Jersey, Mr Dhanush Reddy, 31, was swept into the 90cm mouth of a storm sewer pipe, according to the news site Patch. Mr Reddy's body was discovered Thursday in Piscataway, nearly 8km away.

Still others, like Rabbi Shmuel Dovid Weissmandl, a dedicated patron of the Yeshiva of Nitra Rabbinical College in Mount Kisco, New York, died on the road as their cars flooded. While the torrents came down on Wednesday evening, Rabbi Weissmandl desperately telephoned his son after his car was trapped in deep water as he tried to drive home through the storm.

The son, Moshe Weissmandl, asked a Jewish aid group, Chaverim, to help. After hours of searching, his father's car was found submerged on a ramp to the Saw Mill River Parkway. It was empty. Rabbi Weissmandl's body was not recovered until Thursday morning.

Many of the flood's victims lived in basement apartments, some of which were subterranean dwellings carved out illegally from larger homes and may have lacked the emergency egress required of legitimate apartments. Comparatively low-cost living spaces, they are a refuge of thousands of the city's poor, even as they are known to be firetraps.

Overnight, the basements became traps of water.

As the walls began to leak in their basement apartment on 183rd Street in Hollis, Queens, and the water reached their ankles, the Ramskriets - father, mother and two sons - hustled to get their things. Suddenly, they heard a collapse, said Mr Dylan Ramskriet, one of the brothers, and a gush of water shoved them through the pitch-black apartment as the walls caved in.

The torrent swept his father, Dameshwar, across the home, as he clutched for the hand of his wife, who was known as Tara.

"I tried to hold on to my wife, and she was trying to hold on to me," he said on Thursday. He began to cry. "But the water pushed me away and I couldn't feel her hand anymore."

Ms Tara Ramskriet and their 22-year-old son, who went by Nick, both drowned.

As the waters receded on Thursday, Ms Sabrina Shivprasad, a family friend, stood outside the apartment, its wall punched in by the cresting water, exposing what once was a family home.

"When you saw the husband, you saw the wife," Ms Shivprasad said. "They were always together, they were like shadows to each other."

In Elizabeth, New Jersey, two men and two women, aged 72 to 33, all residents of the Oaks at Westminster apartment complex, were killed as the Elizabeth River rose into their ground-floor apartments, according to Mr Chris Bollwage, the mayor. Their names had not yet been released.

Raw sewage had sluiced through the Oaks complex, and on Thursday, all 600 residents were being evacuated, guided onto school buses en route to temporary shelters, Mr Bollwage said. The river had risen between 2.5m and 3m above its banks, he said; waterfront apartments lay with their doors smashed open, mud swirled across exposed living rooms. "It is really a true tragedy," he said.

As the water rushed through the single window and single door of an apartment converted from a cellar in Cypress Hills, Brooklyn, Mr Ricardo Garcia, 50, and Mr Oliver De La Cruz, 22, roommates, struggled to make it out against the onslaught. They only realised their third roommate, Mr Roberto Bravo, a retired construction worker, was still inside when they heard his screams.

Mr De La Cruz recalled the trauma on Thursday, while inspecting the ruins of his home. At his feet was a photo of Mr Bravo, smiling in a tuxedo, washed up in the flood.

Mr De La Cruz recalled hearing Bravo's pleas of "Ayudame por favor": "Help me please." But the waters were too high for the men to go back inside for their roommate.

Soon they stopped hearing his voice.