The humanitarian organisation, which has repeatedly called for an immediate ceasefire between both parties, warned of the impact upon children as the group itself received news that beneficiaries of its programs had lost their lives in Gaza.
"It is devastating to hear that more children in our programs have been killed or injured over the past couple of days," Costello lamented. "We have had confirmation that a family of six, that World Vision was helping, has been killed."
The United Nations has estimated that 170 children have died since the outbreak of violence began.
World Vision has worked the provide assistance to poor and vulnerable families in the Gaza Strip since 2001, but has been forced to temporarily suspend its operations in the area due to the violence.
Some children receiving psychosocial support from the aid organisation have spoke of the horrors witnessed firsthand.
11 year old boy, Khaled, said, "I have really bad nightmares, as I saw my sister and my cousin shredded and cut into pieces."
A 7 year old girl who lost her family said, "I am drawing pictures. I am drawing what I have seen; the three missiles that struck my house and the corpses of my family; my mother, my father, and my sister."
An estimated 125,000 children in the area are in need of psychosocial support, according to World Vision.
To donate to World Vision Australia's Emergency Preparedness Fund call visit www.worldvision.com.au/emergencies