A mother has pleaded guilty to murdering three of her seven children and trying to kill a fourth by driving into a lake at Wyndham Vale in Melbourne’s south-west.

Akon Guode, 37, showed little emotion as she pleaded guilty to murdering her one-year-old son Bol and four-year-old twins, Hanger and Madit, and attempting to murder her five-year-old daughter Alual in 2015.

The mother’s plea in the Victorian Supreme Court came at a mention hearing before she was due to stand trial.

Guode’s three children were killed when the car they were in crashed into a lake. Photo: ABC/Supplied

As the charges were read to her, through the help of an interpreter, the only words she said were “guilty” to each charge.

Passersby and emergency services frantically tried to help Guode and her children after her car plunged deep into a Wyndham Vale lake.

A police statement publicly released in July last year alleged Guode spoke about killing herself and her children on the day of the tragedy.

A court hearing was previously told she drove by a lake at Wyndham Vale five times before “deliberately and consciously” driving into the water.

Guode came to Australia from South Sudan to escape war after her first husband died. A court heard she had large debts and had sent close to $100,000 to family in South Sudan since 2008.