A four-year-old boy has died in hospital days after his youngest siblings perished in a shed fire on a property in Victoria.

The boy and his three siblings were playing together in the rear shed of a Corio property near Geelong on Sunday morning when it caught alight.

Three-year-old Saige McGregor and 18-month-old Ashlynn McGregor died at the scene while the four-year-old, Isaac McGregor, and his six-year-old sister were flown to the Royal Children’s Hospital.

Victoria Police confirmed the boy died in hospital on Wednesday afternoon while his six-year-old sister remained in a critical condition.