A five-hour police operation following a suspected bomb scare in Brussels city center turned out to be a false alarm.

Police noticed a man near the Place de la Monnaie, wearing a winter coat with protruding wires. He was arrested and questioned. The man turned out to be a student of nuclear radiation at a local university and was researching radioactivity in the city.

The operation resulted in the lockdown of a large section of the city and the evacuation of several shops. Special forces and bomb disposal units were called in to assist.

The incident came one day ahead of Belgium’s National Day, with security already heigtened in Brussels following the Bastille Day attack that left 84 people dead.