The Latest on the attacks on Brussels in which 31 people died (all times local):

11:25 a.m.

Belgian prosecutors say three people have been ordered held on charges of participating in terrorist group activities

They were among four people detained during Sunday searches in Brussels and the northern cities of Mechelen and Duffel.

Belgian prosecutors did not release details on the alleged terrorist actions or whether they were linked to the March 22 suicide bombings at Brussels airport and in the Brussels subway.

The fourth person has been released without charge, according to a statement from the Belgian Federal Prosecutor's Office Monday.

Those charged by the investigating magistrate were identified only as Yassine A., Mohamed B. and Aboubaker O.

10:45 a.m.

A week after devastating suicide bomb attacks, Brussels Airport will test its capacity to partially resume passenger service. But it's too early to say when service might actually resume, an airport official said Monday.

Florence Muls, the airport's external communications manager, said 800 staff members on Tuesday will test temporary infrastructure and new arrangements designed for passenger check-in. The Belgian government must approve the new system, Muls said, before Brussels Airport can resume handling passenger traffic.

Two suicide bombers on March 22 caused great damage to the airport's departure hall, and along with another suicide bomber who blew himself up on a Brussels subway train, killed at least 31 people and injured some 270.