Two people were arrested in Brussels, Belgium, on suspicion of planning attacks during the holidays said the federal prosecutor’s office on Tuesday. The two suspects were arrested following searches on Sunday and Monday in the Brussels area, the Liege region and Flemish Brabant.

The prosecutor’s office said that “the threat of serious attacks that would target several emblematic places in Brussels and be committed during the end-of-year holidays.”

Brussels authorities seized military-type training uniforms, propaganda materials from the Islamic State group and computer materials. No weapons or explosives were found. Six people were taken in for questioning, four were released and two were arrested.

No additional details were made public but the probe was not connected to the November 13 attacks in Paris.