Belgian police arrested 21 more people in raids in and around Brussels by Monday afternoon, searching for those behind the deadly attacks in Paris 10 days ago, while the city remained in lockdown for a third day.
Belgium announced terrorism charges related to the attacks against an unidentified fourth suspect, who was among 16 people detained Sunday. The 15 others arrested were released.
Belgian Prime Minister Charles Michel said Monday that Brussels will maintain its highest security alert level, which will be reviewed again next week. Schools and the metro system are set to re-open on Wednesday, he added.
"We are still confronted with the threat we were facing yesterday," Michel told a news conference.
Separately, police said an explosive vest was found in the southern Paris suburb of Montrouge. The explosives were the same type used in the Paris attacks, according to the Associated Press.