A 52-year-old woman who was driving a car that slammed into a Sydney primary school, killing two eight-year-old boys, has been charged with dangerous driving occasioning death and negligent driving.

Key points: It is understood Maha Al-Shennag's is a parent of a student at the school

It is understood Maha Al-Shennag's is a parent of a student at the school Police will determine whether there were any mechanical problems with the vehicle

Police will determine whether there were any mechanical problems with the vehicle They will also inspect Ms Al-Shennag's mobile phone

Maha Al-Shennag drove a Toyota Kluger into a classroom of 24 students at Banksia Road Public School about 9:45am on Tuesday, injuring more than 20 people.

Two boys who were critically injured in the incident later died in Westmead Children's Hospital.

Two eight-year-old girls were also taken to Westmead in a stable condition, and one nine-year-old girl was taken in a serious condition.

It is understood Ms Al-Shennag is a parent of a student at the school.

Children place flowers at the gate of Banksia Road Public School in memory of the victims of the crash. ( ABC News: Jean Kennedy )

Police will examine the vehicle involved to determine whether there were any mechanical problems.

They will also inspect Ms Al-Shennag's mobile phone as they investigate whether distraction was a factor in the incident.

The crash was described as a "scene of carnage" unfolding into "pandemonium" and NSW Ambulance sent 16 vehicles to the incident.

One student, who cannot be identified, said she saw a teacher faint while others loaded children into ambulances.

Parents collected their children from Banksia Road Public School. ( AAP: Paul Braven )

"They were all just covered with blood. It was very bad," she said.

Loading

One of the first responders, a local resident, helped lift the two-tonne SUV which had trapped one of the boys who later died.

Chaplains also attended the scene and the family members of the two students who died had received counselling.

The school announced on Facebook it would be open on Wednesday, with additional support for staff and students.

Vigil held outside school

More than 100 mourners took part in a minute's silence at a vigil held outside the school on Tuesday evening.

Donna Agha, whose children knew the boys that died, said earlier that day she called around trying to tell parents about the incident at the school.

"We all know each other. It's a family. I was calling everyone, 'go check the kids', some parents knew some parents didn't," she said.

"No-one expects anything to happen like this … I think all of our kids need counselling, it was horrific."

"Stick together as a community we'll have difficult days ahead," Local MP Jihad Dib said to the gathered crowd.

"Always keep the families in our thoughts."

Ms Al-Shennag was charged with two counts of dangerous driving occasioning death and one count of negligent driving, was granted bail and will appear at Bankstown Local Court on November 29.

She was uninjured and her licence has been suspended.

Police said they believed the incident was a tragic accident and not an intentional act.