The child was hit by a bus outside the school in Sydney's south-west

An emergency response was underway after the 10-year-old boy was struck.

(7news.com.au) A 10-year-old boy is fighting for life after being hit by a bus outside a school in Sydney’s southwest.

Emergency services responded to the incident, which occurred about 2.50pm on Wednesday outside Macarthur Anglican School in Cobbitty.

Police, paramedics and a NSW Ambulance chopper were deployed to the scene.

Critical care paramedics tended to the boy, who has since been taken by road to Liverpool Hospital in a critical condition.

The bus driver, a 60-year-old woman, is undergoing mandatory testing and is assisting police.

Emergency services are responding. Credit: 7NEWS

An investigation into the circumstances surrounding the crash has been launched.

Anyone with information about the incident is being asked to contact Crime Stoppers.