SEOUL — At 4:40 p.m. on Monday, the 13-year-old girl texted her 72-year-old grandmother who was in the hospital, wishing her well and saying that she was praying for her quick recovery.
“How sweet of you, my little puppy!” the grandmother texted back.
That was the last time she talked with her granddaughter.
Four hours later, floods triggered by one of South Korea’s heaviest rainfalls gushed down the steps into the three-room, semi-underground home in southern Seoul where the teenager had lived with her mother, 47, and her aunt, 48.
The family had moved into the house seven years ago. They knew the low-lying district was prone to flooding, but it was cheap and close to a government welfare center where the aunt, who had Down syndrome, could get help.
The water rolled down with such force that the family could not push their only door open, according to neighbors and emergency officials. The girl’s mother banged on the door and called her neighbors for help. The neighbors called the government’s 119 emergency response hotline on the family’s behalf, but so many flood victims were dialing in that their calls did not go through.
Two neighborhood men tried to rescue the family through the house’s street-level window, but they could not go through the anti-theft, steel grating blocking the window. “The water filled the house so quickly we couldn’t do anything about it,” Jeon Ye-sung, 52, a neighbor, told reporters.
Mr. Jeon rushed home on Monday evening after his daughter told him on the phone that the water was gushing through the windows into their own semi-underground home. He broke the windows to rescue his three daughters. But he and another neighbor could not reach his neighbors.
By the time rescue officials pumped the water out early Tuesday, they found the family of three dead.
South Korea’s urban poor often live in banjiha, or semi-underground homes. The flood hazard of these underground homes was dramatically depicted in the South Korean movie “Parasite,” which became the first foreign-language movie to win the Academy Award for Best Film in 2020.
One of the nine dead was a woman in her 50s who also lived in a semi-underground home in Seoul. She fled the floodwater but returned to her home to rescue her cat and didn’t make it out alive.
In Seoul, a city where sky-high housing prices are one of the biggest political issues, living high and dry in tall apartment buildings built by the country’s conglomerates like Samsung and Hyundai is a status symbol.
But the poor often live in cheap, damp and musty banjiha. Hundreds of thousands live in such homes in the congested metropolitan area, where they struggle to find jobs, save money and educate their children to overcome growing inequality.
Over the years, Seoul has offered to help those living in such basement apartments, providing them with pumps and other equipment to fight floods. It has also renovated sewer systems in low-lying districts to help drain rainwater more quickly. The government has urged those living in semi-underground basements to move to state-owned apartments with cheap rents.
Still, thousands of families live in banjiha, fearing floods each monsoon season. They build small dikes with sandbags around their homes. When the floodwater recedes, they put their clothing and furniture in alleyways to dry. In a survey in 2020, more than half of the 500 semi-underground households in two districts in Siheung, just southwest of Seoul, reported their homes submerged in rainwater.
“When I returned home from work, I found my banjiha under water,” a semi-underground dweller wrote on the South Korean web portal Naver on Tuesday. “It felt as if heaven had crashed down on me.”
On Tuesday, when President Yoon Suk-yeol visited the neighborhood where the family of three died, their home was still filled with waist-high floodwater. Pillows, furniture and plastic bags floated inside. Mr. Yoon had to squat on the street outside to look down into the home through the street-level window.
The neighborhood was strewn with bags of garbage, rain-damaged furniture and electronics that families dragged out of their basement homes. “There is hardly anything we can salvage,” said Park Kyong-ja, 77, who has lived in the neighborhood for 26 years.
Choi Tae-young, the head of the Seoul Metropolitan Fire and Disaster Headquarters, blamed the floodwater for blocking the door of the family’s home. But neighbors accused the government of failing to alert residents to the coming floods. The city did not warn of the danger of a nearby stream overflowing until 9:21 p.m. Monday, according to local media and neighbors.
From inside their home, the family of three called neighbors between 8 p.m. and 9 p.m., appealing for help because they could not get out. The teenager’s mother, who was identified by the police and local media only by her last name, Hong, also called her mother in the hospital at 8:37 p.m., saying that she could not open the door because of the floodwater, according to the daily newspaper JoongAng Ilbo.
“When I got out and rushed to their home, it was already filled with water and I could not see the inside,” Kim In-sook, a neighbor, told reporters. Police and firefighters could pump out the water only hours later.
Hong Seok-cheol, 46, who lives in a semi-underground home next door, left at 7:45 p.m. on Monday to eat out with his wife. When the couple returned home 40 minutes later, they were shocked to find the alleyway flooding. Their home was filled with water.
“The rain came so fast and furious and the pressure on drainage pipes underground was so strong that they burst open, worsening the flood,” Mr. Hong said. “There was no way my wife and I could have made out if we had been trapped inside.”
Some of the household items belonging to the family of three sat outside the four-story building on Wednesday, including a white teddy bear. In the underground garage, four cars were caked with mud.
“The torrential rainfall was the worst in 115 years,” Mr. Yoon, the president, said during a meeting with emergency response officials on Wednesday. “The poor and the weak are more vulnerable to natural disasters. Our country will become safe when they feel safe.”