Four Newman College students were taken to hospital after a tree branch fell on them during their recess break yesterday.
About 25 middle school students were underneath the tree, believed to be a river gum, when it fell.
The branch reportedly sounded like a gunshot as it fell, frightening many of the mainly Year 7 and Year 8 students.
Newman College principal Bernie Boss said a number of the students had scratches and bumps and he was grateful none of the children sustained serious injuries.
Mr Boss said the trees at the school were examined by a tree specialist after the incident and he did not hold any safety concerns for any of the other trees in the courtyard.
The four affected students received treatment at Sir Charles Gairdner Hospital for minor injuries.