PARIS — Forces from the Islamic State group struck in "an act of war" Friday night, killing at least 127 people, President François Hollande said Saturday after an emergency meeting of the high level defense council.

"An act of war, prepared, planned from abroad with domestic complicity that the inquiry will uncover," Hollande told journalists at the Champs Elysées president's office after the meeting. "This is a barbarous act".

France will employ all legal means, and with the help of allies, strike the forces of Daesh, or the Islamic State, "without pity," Hollande said.

The head of state, who announced a state of emergency after the deadly attacks on Friday night, declared three days of national mourning.

Among the measures put in place, military and police force will patrol the streets of the capital, which has been put under the highest security alert.

"We are at war," Patricia Adam, head of the National Assembly parliamentary defense committee, said on France Info radio. "We are in an asymmetric war."

France has boosted the defense budget to tighten domestic security and adopted a law extending intelligence surveillance powers, she said.

The killings on Friday took place in public places including restaurants, a concert hall, and at a football stadium where Hollande was attending a friendly soccer match between France and Germany.

Some seven or eight gunmen attacked civilians, firing Kalashnikov assault rifles and then detonated suicide bombs.

Bomb attacks took place in the capital during the Algerian war for independence, but this was the first time suicide bombs were used, Alain Bauer, a criminology specialist, said on France Info.

The attackers killed at least 80 at the Bataclan concert hall in the east west of the capital, making that the most deadly of the attacks.

US President Barack Obama, German Chancellor Angela Merkel and British Prime Minister David Cameron were among the heads of state and government who gave messages of support to France.

ISIL issued an online statement claiming that eight insurgents armed with assault rifles and suicide belt bombs mounted the attacks, BFM TV and Agence France-Presse reported.

The slayings follow the deadly January attack by fundamentalist extremists on civilians and journalists at the Charlie Hebdo weekly.

France has taken part in the allied aerial intervention against the ISIL forces in Syria and Iraq, and Hollande recently said the Charles de Gaulle aircraft carrier would be sent to support the airstrikes.