Police Superintendent Alan Chung said the killings might have been related to her troubled relationship with her husband or that it was possible the woman did not want her three daughters to be taken care of by other people after a divorce.

He added that police were considering all possible motives.

Muhammad Arshad, the chief imam of Hong Kong, said the woman’s husband had approached him several months ago for help with the couple’s marriage problems.

The head of the Kowloon Mosque and Islamic Centre said the husband had told him his wife did not want to stay with him because of his extramarital affairs and would not allow their daughters to see him.

“He sought reconciliation and to live with his daughters, because he loved his daughters very much. And she didn’t want to give her daughters to her husband,” he said.

Chief Secretary Eric Chan Kwok-ki said he was saddened by the incident and appealed to parents not to take their troubles out on their children.

“We have to avoid these tragedies, one is too many,” he said.

Hong Kong man, 66, suspected to have killed himself after choking ill daughter, 39

Chung, of the Kowloon West regional crime unit, said the woman moved into the about 200 sq ft subdivided flat on the area’s Kweilin Street with her daughters about a year ago after she suspected her husband of having an affair.

He added the police investigation showed she did not have a record of mental illness and that she had been seen by social workers because of her domestic problems until the end of last year.

She and her daughters lived on welfare money.

The source added the woman would be sent to hospital for a psychiatric assessment because she was incoherent and talking about ghosts.

The woman was said to have been acting abnormally and speaking incoherently when she had dinner with her mother, younger brother and her three daughters in the New Territories on Sunday night.

Woman and 5-year-old son fall to their deaths at Hong Kong building

But her family did not take her to see a doctor and her younger brother drove the woman and children home.

The woman phoned her mother on Monday morning and said she had killed the girls.

Officers were called to the home after they were alerted by the girls’ mother and brother at about 11am.

Chung said the woman answered the door when officers arrived, but the bedroom door was locked.

The little girls were found unconscious on a bed after officers broke the door down.

The woman at the time claimed her husband had killed her three daughters and stabbed her.

Chung said the children were rushed to Caritas Medical Centre, but they later died.

Two pillows and some blood were found on the bed and bedroom floor.

“Blood was found at the mouth and nose of one of the girls. We don’t rule out that the three victims were smothered to death with the pillows. An autopsy will be carried out to ascertain the exact cause of the deaths.”

Officers later traced the husband, who was taken to the flat to assist police with their inquiries.

The woman was still in police custody on Monday evening, but had not been charged with an offence.

Chung appealed to the public to show more concern for relatives, friends and neighbours and to keep an eye on them.

He said communities should develop a neighbourhood mutual help mindset, which might help prevent similar incidents.

The flat is in an eight-storey tenement in Sham Shui Po, one of the city’s poorest districts.

Susan Chi, a volunteer who was working at the office of the Society for Community Organisation, an NGO on the second floor of the building, told the Post the family lived on the fifth floor.

The volunteer said she had heard an unusual noise upstairs at around 11am when police arrived at the scene and knocked on one of the doors.

Chi said she later saw police holding a girl whose face was pale and another child was on a stretcher. She added both girls were motionless when police rushed them down the stairs.

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“I was heartbroken to see this happening in front of my eyes,” she said.

Chi, a regular visitor to the building, said she rarely bumped into the family. She added she believed they had only recently moved into a subdivided flat.

The Social Welfare Department said the woman and her three daughters were an active case for an integrated family service centre operated by an NGO.

“The department will approach the relatives concerned as soon as possible and render appropriate assistance according to their welfare needs,” officials said.

Staff from the department will also set up a mobile service counter with an NGO outside exit C2 of Sham Shui Po MTR station at 4pm.

Social workers will provide help and service information to people in need. They also operate a 24-hour hotline on 2343 2255 for phone counselling, support and referral services.

Secretary for Home and Youth Affairs Alice Mak Mei-kuen said authorities in the coming days would arrange seminars offering emotional support to affected residents, as well as find ways to reach out to more “hidden” families.

The Education Bureau said the children’s school had set up crisis management teams to provide help to teachers and students affected by the incident.

Jeffrey Andrews, manager of NGO Christian Action Centre for Refugees, said the services currently available for people from various ethnic minority groups were unable to fully meet their diverse needs.

“Mosques, churches and temples, they’re doing their best to be a place of community support. I think obviously the NGOs where we work need more resources. We’re trying our best to get more visible out there, to let the community know we are here to help,” he said.

The city in recent years has recorded several domestic tragedies involving parents and children.

Domestic violence cases up sharply in Hong Kong since start of pandemic

A 30-year-old woman and her five-year-old son fell to their deaths from the Cullinan West residential block in Cheung Sha Wan in a suspected murder-suicide case on May 1. The woman’s husband was not in the city at the time of the incident.

A pregnant woman attempted to throw herself off a building in Sham Shui Po in September last year. She was later arrested on suspicion of murdering her five-year-old son.

Another case in 2021 saw a businesswoman and her five-month-old daughter fall to their deaths from their penthouse flat in an upscale residential block.

Preliminary investigations suggested the woman had been suffering from postnatal depression.

Police handled six reports of homicide between January and March this year. Seven cases were reported in the same period last year.

The force dealt with 288 reports of domestic violence over the same period, up 17 per cent from 246 cases in the same period last year.