Girl on bus which hit and killed her mother

An 11-year-old girl was on the school bus that ran over and killed her mother. Photo / Thinkstock

An 11-year-old girl was on the school bus that ran over and killed her mother, and narrowly missed her baby sister, in Sydney's north.

The 38-year-old woman was killed when she was struck at the intersection of Hannah and Beecroft Roads in Beecroft shortly after 3pm local time on Wednesday.

She was carrying her 11-month-old baby girl, who was hurled out of her arms but miraculously escaped injury.

The woman died at scene, police said in a statement on Thursday.

The bus was full of students from Beecroft Primary School returning from an excursion, among them was the woman's older daughter.

"The 11-year-old daughter of the deceased lady, the mother, was on the bus with other school children," police duty officer Darren Jameson told Macquarie Radio on Thursday.

"Fortunately, she didn't see the incident but she was on the bus.

"It's a tragic day, not only for the family but for the witnesses and the bystanders."

Police have interviewed the 69-year-old bus driver, who was taken to hospital for mandatory blood and urine tests.

The students are undergoing counselling.

The bus has been seized for forensic examinations.

Crash investigators have renewed their appeal for witnesses to come forward.

-AAP