Bankstown police investigates an incident of a child falling from the third floor

The child is suffering from critical head injuries

Police Source: AAP (AAP Image/Dan Himbrechts)

A seven-year-old boy has suffered critical head injuries after falling three floors from a unit block in Sydney's southwest.

The boy fell from the bedroom window at the block on Chapel Road in Bankstown at about 7.20pm on Monday.

Family members rushed the boy to Bankstown Hospital, but he has since been transferred to Sydney Children's Hospital, Randwick, with critical head injuries.

Detectives from Bankstown are investigating the incident.