Community vigil for siblings who died in shed fire

The Corio community has gathered to pay tribute to three young siblings killed in a shed fire. (Julian Smith/AAP PHOTOS)

A regional community has met for a vigil for three young siblings killed in a shed fire in southwest Victoria.

Four children 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.

Saige, 3, Ashlynn, 18 months, and Isaac McGregor, 4, died in a shed fire at their Corio home.

Their six-year-old sister and four-year-old brother Isaac McGregor were flown to the Royal Children's Hospital in a critical condition.

Victoria Police confirmed Isaac died in hospital on Wednesday.

Members of the family's local community gathered on Saturday evening to pay their respects and show support at a vigil at Rosewall Reserve in Corio.

Mourners have brought flowers, battery-operated candles, teddies and balloons to a community vigil.

"The family needs all the support they can have," organiser Torii Janine Sanderson told AAP.

"As a community, we should all stand together and do what we can to help."

Mourners brought flowers, battery-operated candles, teddy bears and balloons in remembrance of the children.