The Islamic State claims responsibility for attacks in Paris that left more than 125 people dead.
Authorities delivered an update on the attacks today, saying more than 350 were injured — nearly 100 of them are in critical condition.
"We can say that very likely there were three teams of terrorists who caused this barbarous attack," said Paris prosecutor Francois Molins. "So we need to determine the authors, their accomplices, the orderers, the mandators, and the financing."
France's interior minister has given local authorities permission to impose curfews, if necessary.
Armed guards are patrolling the Eiffel Tower and other sensitive locations across Paris.
Several locations were targeted last night in what is being described as the worst attack on France since World War II.
Terrorists opened fire inside cafes and suicide bombers detonated explosives outside of the national stadium.
Dozens of concert-goers were murdered after being held hostage for nearly an hour.
French President Francois Hollande called it an act of war and vows to retaliate against the Islamic State quote "without mercy."
He declared three days of mourning and raised the nation's security to its highest level.
Parisian mayor Anne Hidalgo says the city is a happy and diverse place filled with culture, and that attackers were looking to destroy that.
"This model of living together which is so evident in our city in unbearable for fanatics, it's unbearable for those who want to reduce the whole of mankind to silence," Hidalgo said.
French officials say all of the eight attackers are dead — seven of them took their own lives.