Belgian authorities announced Monday that they have detained five people, including two brothers, after two days of raids related to the Paris attacks.

The federal prosecutor’s office said two people were detained following a house search Monday in the Laeken district of Brussels. On Sunday evening, another Brussels house was searched on orders from an investigating judge specializing in terrorism. Two brothers found there were taken in for questioning, as well as a friend.

The prosecutor’s office said an analysis of phone records led to Sunday’s search. Authorities said they found no weapons or explosives at either residence, and did not identify those detained.

The investigating judge will decide later on whether to keep the five in custody. Eight other people detained earlier in Belgium have been ordered held in preventive custody.

The Islamic State group claimed responsibility for the Nov. 13 Paris attacks, which left 130 people dead. A European Union summit last week resolved to continue the EU’s effort against violent extremism, and called for wide-ranging measures including systematic checks on people crossing Europe’s external frontiers.

In France, people traveling on high-speed trains from France to Belgium and the Netherlands now must pass through new metal detectors. As of Monday, the detectors were operational at Paris’ Gare du Nord station for all passengers taking Thalys TGV trains, which connect Paris, Brussels and Amsterdam.

The open French-Belgian border has been under special scrutiny since the attacks by extremists with ties in both countries. In August, a Paris-bound Thalys was the scene of a thwarted attack when American passengers subdued an Islamic extremist gunman who had boarded in Brussels.

There are already security checks on high-speed trains from France to Britain. There aren’t any metal detectors for slow trains between France and Belgium, or on routes from France to other neighboring countries.

(AP)