France's main Jewish students union has plastered walls around Paris with posters bearing the faces of French citizens believed to be held hostage by Hamas in their war with Israel. Very little is known about the hostages locked away in the Gaza Strip or whether some of those captured during the Oct. 7 surprise attack on Israel have been killed in the Jewish state’s brutal counter-offensive. French Foreign Minister Catherine Colonna said Sunday during a visit to Israel that 19 French citizens are known to have been killed and 13 others are missing.