A wave of co-ordinated attacks has left more than 150 people dead in scenes of carnage across Paris.
The attacks took place at a concert hall and several bars and restaurants in eastern Paris, as well as the Stade de France national stadium north of the city centre.
A total of eight militants were killed, including seven by their suicide belts, a source close to the investigation said.
Four of the attackers were killed in the Bataclan concert hall, three more died near the national stadium and a fourth was killed in a street in eastern Paris.
More than 200 people were wounded, including 80 seriously, a source close to the investigation said.
At the Bataclan, black-clad gunmen wielding AK-47s stormed into the concert hall on Friday night, and fired calmly and methodically at hundreds of screaming concert-goers.
Witnesses said the attackers shouted "Allahu akbar" ("God is great") and blamed France's military intervention in Syria as they sprayed bullets into the crowd watching US rock band Eagles of Death Metal.
Three of the attackers blew up suicide vests as police launched their attack, several sources said. The fourth was hit by police fire and blew up as he fell.
"There was blood everywhere, corpses everywhere. We heard screaming. Everyone was trying to flee," said Pierre Janaszak, a radio presenter who attended the concert and hid with several others at the venue.
"They had 20 hostages, and we could hear them talking with them," said Janaszak.
In the north of the city, at least five people were killed in three explosions near the Stade de France national stadium where France were playing Germany in an international football match, security sources said.
President Francois Hollande was attending the match and had to be hastily evacuated.
A Cambodian restaurant near the concert hall was also attacked, with further deaths reported.
Hollande declared a state of emergency across the entire country and cancelled his trip to the G20 summit, which is due to take place this weekend in Turkey.
Prosecutors said at least five attackers had been "neutralised" in total.
The most bloody of the attacks was at the Bataclan, where police said around 100 people were killed.
"We heard so many gunshots and the terrorists were very calm, very determined," Julien Pearce, a reporter for France's Europe 1 radio, told CNN while the hostage crisis was still under way.
"They reloaded three or four times ... and they didn't shout anything. They didn't say anything."
He said friends were still inside as he spoke.
"They are hiding in some kind of room in the dark and they text(ed) me, and they are very afraid, of course, and they are waiting for the police to intervene, but it's been over two hours now and this is terrible."
Hundreds of police had gathered outside and armed officers eventually stormed the venue at around 11.35pm (local time) accompanied by a series of explosions.
At the Stade de France, spectators flooded the pitch as news of the attacks spread before organisers started evacuations.
An extra 1500 soldiers were mobilised to reinforce police in Paris, Hollande's office said, while mayor Anne Hidalgo called for residents to stay home.
US President Barack Obama led a chorus of global condemnation, saying it was "an attack on all of humanity".
German Chancellor Angela Merkel and European Commission chief Jean-Claude Juncker said they were "deeply shocked" by the attacks.
France has been on high alert since the attacks in January against Charlie Hebdo and a Jewish supermarket that left 17 dead.
Security had begun to be stepped up ahead of key UN climate talks to be held just outside the French capital from November 30, with border checks restored from Friday.
President Barack Obama has condemned the night of horror in Paris as an "attack on all of humanity" and vowed the United States will stand firmly by France.
"Those who think that they can terrorise the people of France or the values that they stand for are wrong," Obama said in a hastily convened news conference at the White House.
Obama was briefed on the series of attacks, which have killed more than 100 people, by his counterterrorism advisor.
"We are reminded in this time of tragedy that the bonds of liberte, egalite, fraternite, are not just the values French people share, but we share," the president said, citing France's national motto.
"Those go far beyond any act of terrorism or the hateful vision of those who perpetrated the crimes this evening."
The Department of Homeland Security reported there was "no specific or credible threat to the United States" after the attacks.
But authorities in New York were on a heightened state of alert.
Counterterrorism police reinforcements were deployed to crowded public places as a precautionary measure.
Units were also sent to the French mission to the United Nations and the French Consulate.
The New York Police Department said detectives in its intelligence division were "conducting liaison activities to assist the Paris police in any way possible".
Obama stressed his resolve in tackling terror.
"We're going to do whatever it takes to work with the French people and with nations around the world to bring these terrorists to justice and to go after any terrorist networks that go after our people."
AFP / RadioLIVE / 3 News