President Francois Hollande says France will be "merciless" against those behind the deadliest attacks in the country in decades.
Visiting the Bataclan, a popular music venue where more than 100 people were killed in eastern Paris, Hollande called the attacks an "abomination" and "barbarism."
He called on the French to remain united. "We will lead the fight. We will be merciless."
The night of terror unfolded with three suicide bombings outside the Stade de France during a friendly international soccer match between the French and German teams.
Hollande, who had to be evacuated from the stadium, later vowed that the nation would stand firm and united.