Mother Killed and 2 Children Critically Hurt in Hammer Attack at Home

A 43-year-old woman was dead and her 5-year-old son and 3-year-old daughter were in critical condition on Wednesday after they were bludgeoned with a hammer in their Brooklyn apartment by a man who also lived there, officials said.

A 47-year-old man initially taken into custody as a person of interest in the attack was subsequently arrested, John Chell, the New York Police Department’s chief of patrol, said at a news conference. The police did not immediately identify either the victims or the suspect.

The children, Chief Chell said, were “fighting for their lives as we speak.”

The attack occurred shortly before 3 p.m. in a three-room apartment on 52nd Street in the Sunset Park section that the victims and the suspect shared, Chief Chell said. The victims lived in one room; the suspect and his 9-year-old son lived in another; and a single person lived in the third room, the chief said.

Officers responding to a 911 call about an assault at the building detained the suspect, his body covered with blood, as he was leaving, Chief Chell said.

The officers then went to the apartment where the attack occurred and found the mother and her severely injured children, the chief said.

The motive for the attack was not immediately clear, and the investigation was continuing, Chief Chell said.

The neighborhood where the assault occurred has a large population of Chinese immigrants. State Senator Iwen Chu, a Democrat who represents the area, said the victims and the suspect were originally from China’s Fujian Province.

Lailing Yu, who lives a block from the crime scene, said she had been horrified when she received a video on her phone of two officers clutching the bloodied children.

“I was shocked,” Ms. Yu said, as she stood with others who had gathered outside the five-story brick building where the victims and their attacker lived. “Because the majority of Chinese people try to stay out of trouble.”

She said that talk on the WeChat app she uses to stay in touch with neighbors was that the violence was rooted in a rent dispute. Many Chinese immigrants in the area, she said, live in illegally subdivided apartment that themselves have been illegally sublet.

“It’s different than landlord-tenant disputes, because you can’t go to housing court,” Ms. Yu said.

Ms. Chu said she had learned from the police that the man accused in the attack contacted a man with ties to the apartment sometime Wednesday and asked him to pick up the suspect’s son.

Arriving at the apartment early in the afternoon, the man found the woman and her children lying in pools of blood in the kitchen area and called 911, Ms. Chu said.

The suspect’s son was taken to a police precinct, where he remained with his mother, Ms. Chu said.

The dead woman’s husband had been sent to Ohio for work and had been trying desperately to return to New York all afternoon, Ms. Chu said. She was not certain of his occupation but said he was most likely employed in the restaurant industry, where it is common for Chinese workers to take jobs in far-flung locales.

“You don’t pick and choose where you can work,” said Ms. Chu, who was at the attack scene to offer her services as a translator for the police and to console community members.

“They don’t know what’s going on,” she said, explaining that people in the neighborhood were on edge after a surge in bias crimes in recent years. “There has been so much anti-Asian hate crime, it triggers them.”

Families living in such tight, and precarious conditions, must endure tremendous strain, Ms. Chu added.

“There’s so much stress, mental, financial, emotional, family,” she said. “But what would cause you to do that?”

Later in the evening, neighbors were still gathered outside the building, chatting in Mandarin while standing on the same swath of sidewalk where they had watched their young children play all summer.

Louis Lin was among those in the crowd. Mr. Lin, a 33-year-old restaurant server, said he lived in an apartment adjacent to the one where the attack occurred. He said he knew something had happened when the police arrived and was terrified when he saw the hallway “covered in blood.”

Mr. Lin said that he and other building residents had regularly heard the sound of arguing coming from the apartment where the victims and the suspect lived. Just two days ago, he said, there was an especially loud dispute that “the entire building was able to hear.”

He identified the two children as David and Yaya and said they had many playmates in the building.

They were “just so lovable,” he said, holding back tears. “How could this be?”

Erin Nolan and Jeffrey E. Singer contributed reporting.