Authorities have closed off a major shopping center in the center of Brussels following reports of a pre-dawn alert.

Police in hoods and military were seen patrolling around at least one major entry to the City 2 shopping center was shut with police cars outside. Media reported that an alert was sounded around 5.30 a.m. and reaction was immediate.

Belgium has been living under a threat level that an attack is possible and likely since the November attacks in Paris, some of whose perpetrators were either Belgian nationals or had lived in Brussels. On March 22, attacks on the Brussels subway and airport killed 32.

The federal crisis center met in a special session early Tuesday.