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Two children have been killed and two others are fighting for life after a shed fire at a property in Corio, near Geelong.
The four children were playing inside the shed when the fire broke out, trapping them inside in what police have described as "a horrific scene".
Neighbour Darren Cheesman told 9News he was "pretty shocked".
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"You don't think it's going to happen down the road from you," he said.
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Victoria Police Inspector Emma Bartel said "it was very much a chaotic scene".
"It's a tragic and awful event that has happened.
"For the sake of the families that are involved, we owe it to them to find out what took place and give them some answers."
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Heartbreak was felt by even the most experienced first responders who turned up at the scene as the tragedy unfolded about 10.30am.
"This is a horrific scene," Bartel said.
"Many of our officers and our fellow emergency services are parents as well.
"There is a lot of this community rallying together for the household, the families that are involved."
It is understood that a mother of at least one of the children was at home at the time. She was not injured.
Police are still working out how the children were connected.
The arson squad remained at the scene as they tried to establish exactly what caused the blaze.
At this stage they say the fire isn't suspicious, but rather a tragic accident.
A report will be prepared for the coroner.
Corio is one of the largest suburbs of Geelong, about 67km away from Melbourne.
