A five-year-old girl’s condition has improved after three of her siblings were killed when a car driven by their mother plunged into a lake in Melbourne’s outer-west.

Anger, a four-year-old girl, and her twin brother Madit were killed along with their one-year-old brother Bol as a result of the crash in Wyndham Vale yesterday.

Awel, their five-year-old sister, is in hospital in a serious condition, downgraded from critical.

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A male family member interviewed outside the hospital was asked by reporters if Awel was awake.

“Yes, she’ll be fine,” he said.

Locals have created a memorial of flowers and toys near the lake. Photo: ABC

A female relative said the family was staying strong.

Earlier today, police preparing to question the 35-year-old woman who was driving the car confirmed she is their mother.

She has three older children who were not in the car.

She was taken to hospital immediately after the incident and placed under police guard before she was discharged.

Police confirmed one child died at the scene, another passed away on the way to hospital about 5:30pm (AEST), and the third died in hospital before 7pm.

Superintendent Stuart Bateson said the mother was assisting police with their inquiries, but it was too early to say if she would face charges.

“I can confirm that our investigation, our joint investigation between our major collision investigation unit and the homicide squad continues,” Supt Bateson said.

“I can also confirm that the driver of the vehicle, a 35-year-old woman from Wyndham, is currently assisting homicide investigators.

“I can confirm that she is the mum of the four kids… they were all members of the local Sudanese community.”

Supt Bateson appealed for anyone with information about the family’s situation to come forward.

“We understand that there may be some social, cultural and religious implications impacting on the community, but let me reassure you that we will remain respectful of those issues at all times,” he said.

“We do need to understand what was happening in their lives and we do need to understand what their movements were leading up to the incident.

“So we ask, if you have any information that you think may assist us in understanding the situation, that you call Crime Stoppers or pop into your local police station.”

He said they were not aware of anyone at this stage who had witnessed the car plunging into the lake.

Family ‘shocked’ by what happened

Thomas Kok is a relative of the victims and visited the lake today.

Police divers retrieve the vehicle that plunged into Lake Gladman in Wyndham Vale. Photo: AAP

“We just came to pay our tributes. We spent all night at the hospital,” Mr Kok said.

“It’s shocked everyone. I saw the comments coming (from the community). It makes me feel like people care.

Locals have left toys, flowers and candles beside Lake Gladman, where the car remained submerged overnight.

Mark England, who lives nearby, said it was a “horrific” scene to witness.

“I was at home yesterday and I heard more fire trucks and sirens than I normally hear,” Mr England told ABC.

“I thought it might’ve been a grassfire, so I came down to have a look and I saw the car in the water.”

He said he saw police officers and members of the fire brigade trying to resuscitate some of the children.

“After, I reckon it was probably five or 10 minutes later, they must’ve realised there was another missing person, so they dived into the water and were checking the car and around the reeds … and they did find someone under the water,” he said.

“I think earlier on, when the car first went in, there was reports of people getting into the water and smashing windows to try and get three people out.

“It was pretty horrific.”