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Islamic State militants claimed responsibility for the shooting, in which a French policeman was shot dead, via its Amaq news agency, naming the attacker as Abu Yousif al-Belgiki -- "the Belgian" in Arabic.
"The investigation is continuing. What we can confirm, is that the perpetrator was a French national," Jambon told VRT.
French police have taken into custody three family members of the gunman, a legal source said on Friday.
In November 2015, when Paris was rocked by near simultaneous gun-and-bomb attacks on entertainment sites, two of the 10 known perpetrators were Belgian citizens and others lived in Belgium.