The girl died on the way to hospital after the van was stopped by armed police in the western city of Mons, according to the news agency Belga.
Officers reportedly opened fire on the vehicle when it tried to run them over, but officials say the girl did not die of gunshot wounds.
Cause of deathOn Thursday, local prosecutor Frederic Bariseau seemed to have ruled out the possibility that the girl could have been killed by authorities. "It was not police gunfire that caused this girl's death," Belga quoted him as saying. He said possible causes of death were illness or dangerous driving that had caused the child's head to hit the side of the van.
Bariseau said an autopsy was being carried out to determine the final cause. He refused to confirm reports that the girl or other children had been dangled out of the van's window during the chase.
The prosecutor changed his tune by Friday afternoon, after he was made aware of the results of the examination.
"The autopsy determined that the cause of death was a bullet that entered the cheek," he told the news agency AFP. "The bullet could be of police origin," he added. "We have to assess the evidence."
Read more: Brussels: Refugees wait for asylum in the heart of Europe
Headed for BritainAccording to Belga, 30 people, including four children, were found in the van.
The Belgian media group Sudpresse said those detained included migrants from Iraq, Afghanistan, Iran and Kuwait.
It said the dead girl and her family were Kurds who had recently been deported from Belgium to Germany, and that they had been attempting to reach Britain by way of Belgium.
Many migrants are drawn to the Belgian border region near France on their way to Calais, where they try to board trucks crossing to Britain.
tj/rt (dpa, AFP)
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