Emergency services were called to the oval on Frankston-Flinders Rd in Tyabb at about 6.30pm.
Despite the efforts of paramedics the boy died at the scene.
His attacker sustained gunshot wounds to the chest and was flown to The Alfred hospital in a serious condition.
In a statement, Victoria police said: “Emergency services were called to attend the oval on Frankston-Flinders Road around 6.30pm after a boy sustained head injuries.
“He was treated by paramedics at the scene but has died.
“A confrontation with a man aged in his 50s then took place and the man was shot in the upper body.
“The exact circumstances surrounding the incidents are yet to be established.”
Witnesses told the Herald Sun when officers arrived, the man turned on them with a knife, forcing them to shoot him.
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