Parisian police ordered a partial evacuation of the railway hub on Friday after they found an inactive explosive device in a traveller's bag, according to sources.
The shell was discovered during a random check at the station, which is a stop for trains from London, Belgium, Germany and the Netherlands, four suburban train lines, and the city's two metros.
According to a source, the man who carried the item was a soldier.
Arrivals and departures were briefly delayed before being continued later in the day.
France and Paris, in particular, have endured several deadly attacks committed by Daesh* supporters and radicalised Muslims. The terrorist assaults in Paris on 13 November 2015 were considered the worst in the nation’s history.
*Daesh (also known as ISIS/ISIL/IS) is a terrorist group banned in Russia