A three-year-old boy has been taken to hospital with serious injuries after he was struck by a four-wheel-drive in Sydney's east on the same day that another young boy was killed in an accident outside a Sydney public school.

In the latest accident, at 7.10pm on Wednesday, the three-year-old was playing with friends in Matraville when he ran on to the road and was struck by a Nissan X-Trail, police said.

The boy was dragged under the car but was conscious when paramedics arrived on Lone Pine Parade. The boy was also bleeding from the face and foot. The driver stopped at the scene.

Paramedics took the boy to the Sydney Children's Hospital where he remained on Thursday morning.

Police said the boy's injuries were not life-threatening.

The crash occurred 10 hours after a six-year-old boy died when he was struck by a Nissan Dualis outside Carlingford Public School.

The boy, known only as Akshay, was visiting Sydney from Malaysia with his mother and had been in the country for just a week when tragedy struck.

Akshay and his mother had been walking to school with Akshay's five-year-old cousin Zoe, a kindergarten student at Carlingford Public School, and her sister Elle, 4, when the car hit them as they crossed the school's driveway.

Akshay and Elle were pinned under the car, killing Akshay and breaking Elle's pelvis in two places.

Police have appealed for anyone with information about either crash to contact Crime Stoppers on 1800 333 000 or visit the Crime Stoppers online reporting page.