According to a news brief published by L'Express, members of the Paris Fire Brigade (BSPP) noticed last year that, "the strange, even worrying, behaviour of individuals stationed near certain barracks in the capital".
The scenario has been repeated several times, particularly in the 16th arrondissement. Whilst the fire brigade rushes to what turns out to be a false alarm, one or more lookouts note down and time their route. According to the same source, the authorities fear that, in the event of an attack, this reconnaissance could enable accomplices to hinder emergency services’ access to the scene by placing obstacles along the route. Or, worse still, to carry out a ‘secondary attack’.
The French intelligence services have taken this potential threat into account. In Paris, when the fire brigade comes across this sort of ‘spy’, a report is filed at the nearest police station.