Seven attackers – two of them residents of Belgium – died during the assaults on Friday, authorities said.
The discovery of a suspected getaway car has fuelled suspicion that at least one other may have got away.
France’s interior minister said investigations would show the attacks “were prepared abroad, by a group of individuals based in Belgium.”
Bernard Cazeneuve said the group “benefited from accomplices in France.”
France is marking three days of national mourning for the 129 people who were killed in attacks on restaurants, a concert hall and a sports stadium.
Hundreds of others were injured, many critically.