Mum who killed 3 kids and burned bodies restrained as she bangs head on dock in court

A woman who pleaded guilty to killing her three children and burning their bodies in a house fire had to be restrained in court after repeatedly banging her head on a balustrade in court.

Margaret Dale Hawke, 36, sobbed as details of how she murdered her kids - a 10-year-old girl, a seven-year-old boy and a four-month-old boy - were revealed in the Western Australia Supreme Court.

The court was told the two oldest children had been stabbed and strangled, while the baby had been smothered at their home in the Pilbara town of Port Hedland, Western Australia, in July last year.

The children's bodies were found when emergency services rushed to the home that was engulfed in flames.

The woman admitted to walking into the street after setting her home on fire, with a witness describing her as "really calm" as she watched the house burn, while others said she appeared "really manic", walking back and forth.

Prosecutor Justin Whalley SC said another witness heard the woman say: "He's taken everything from me".

The woman then screamed and cried, saying: "My babies, my babies ... You don't have to suffer any more."

The night before the tragedy, Hawke had sought help from a women's refuge as she was struggling to cope but was burned away because it was full, The West Australian reports.

In a police interview after the incident, the mother-of-three said: "I don't know why I did what I did. Maybe to stop the pain in all of us."

Firefighters put out the blaze and recovered the children, who were believed to have died before the fire began (AAP/Alamy)

Mr Whalley said Hawke told her children she loved them and asked for their forgiveness before killing them.

Some family members were in the public gallery during today's hearing while the children's grandmother and Hawke's mother watched proceedings via video link from South Hedland.

Hawke's lawyer Alana Woldan said the woman's life was plagued by "dysfunction and difficulties" and she was not coping with the responsibilities of being a mother.

Justice Michael Lundberg said he needed time to consider the case and adjourned the sentencing until May 5.

The woman has been remanded in custody where she has been since the day of her arrest.