Three dead after seconds-long Sydney chase

Twelve children have lost their mothers after three young women were killed during a high-speed chase with police in Sydney .

The pursuit lasted seconds, but the fallout will change lives forever after a white Holden Commodore crashed into a power pole when the driver allegedly fled from a random breath test.

Roza Mawen, a mother of four, and Adut Garang, a mother to eight, died in the crash as well as their friend Bianca Goak.

All three women were in their 30s.

One of the victim's children wrote of their grief of the horrific news on Facebook, The Sydney Morning Herald reports.

"This can't be true not my mum noo."

"Can't believe she's actually gone why did you leave me alone.

"What is life now without you. Your (sic) the best mum ever I know you been through a lot I wasn't easy on you but now your resting. An ill always love you mummy."

The tragic crash took place after officers attempted to pull over the car in Marayong about 1am on Saturday.

"The car, we would say, sped away and within a matter of seconds collided with a power pole and now we have three females who are deceased," Assistant Commissioner Denis Clifford told reporters on Saturday.

Two of the women died at the scene, while a third woman died in Westmead Hospital.

A man and a woman who were also in the car are in a serious but stable condition in hospital.

Asst Comm Clifford described the crash as a tragedy.

"There's a lot of people that will be very affected by what occurred tonight," he said.

"A lot of lives that will be changed forever."

Police have launched a critical incident investigation, to be overseen by the Professional Standards Command.