Belgian media say one of them is Salah Abdeslam, suspects in last year`s Paris attacks in which 130 people died. Prosecutors have not confirmed this.
Belgian PM Charles Michel had to urgently leave an EU-Turkey summit in Brussels, a BBC reporter says.
Abdeslam`s fingerprints were found in a Brussels flat raided earlier this week.
Abdeslam, a French national born in Brussels, had lived in Molenbeek before the 13 November attacks.
He has been the subject of a massive manhunt since the attacks, claimed by Islamic State militants.
Brussels raids: `Shots fired` in Molenbeek operation
19 March 2016
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Shots have been heard in the Brussels suburb of Molenbeek as police launched anti-terrorist raids there, wounding two people, Belgian media report.
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