An outpouring of grief has been shared following the deaths of a kindergartener and her baby brother who were fatally hit by a car near a busy highway in Sydney’s south-west.

At about 3.15pm yesterday, emergency crews were called to the intersection of Joseph and Gilbert Street, near the Cumberland Highway in Cabramatta following reports of a crash.

Katherine, 5, and Harry, 1, were killed when they were hit by a car in Cabramatta, Sydney. GoFundMe

Two children have been seriously injured following a crash on the Cumberland Highway.

Two children have been killed in a crash near the Cumberland Highway. Supplied

Police say two children, both under the age of five, were hit by a car at the intersection while being pushed in a pram by their mother.

An online fundraiser set up for the family has raised more than $5000 so far.

The organiser, Patrick Te, named the two children as five-year-old Katherine and 14-month-old Harry.

“Their mother, Sok, was picking up Katherine from school. Katherine, who was in her first year of kindergarten, was excited to go home after just receiving an award,” he wrote.

“As they were crossing the road together, heading back to the car, an oncoming vehicle suddenly struck both Katherine and the pram where Harry was sitting.”

The children were rushed to hospital with critical injuries, where they died. Sok was treated for minor injuries.

Superintendent Tim Calman called it “one of the most confronting scenes” police have seen, but added that the community were “phenomenal” in providing immediate help.

“We’ve had a number of motorists that actually stopped and have collectively moved the vehicle on its side … to get one of the children from underneath the vehicle.”

Calman said multiple onlookers performed CPR on the children.

Their mother, Sok, was taking the children home. GoFundMe

Superintendent Tim Calman said the driver of the vehicle was arrested following the fatal crash.

Superintendent Tim Calman said the driver of the vehicle was arrested following the fatal crash. Supplied

The children were rushed to Westmead Hospital in critical condition, but they died shortly after.

Their 33-year-old mother, suffered minor injuries.

The 56-year-old driver, who was uninjured, was arrested and taken to hospital for mandatory testing.

All southbound lanes on the Cumberland Highway remain closed, and authorities are urging commuters to avoid the area.