A Paris prosecutor says that at least 129 people died and 352 were injured in the attacks, with 99 still in critical condition.
Two French police officials say that authorities have identified one of the suicide bombers who targeted Paris in deadly attacks as a young Frenchman flagged in the past for links with an Islamic extremist activity.
I am deeply saddened by the terrorist attacks in Paris. Please join me in prayer for the victims and their families. #PrayersForParis— Pope Francis (@Pontifex) November 14, 2015
The officials said the man was among attackers who blew himself up after a rampage and hostage-taking in a Paris concert hall.
A Greek official confirms the Syrian passport found on the body of one of the attackers at the Stade de France belonged to someone who had crossed into the European Union as a refugee, through the Greek island of Leros in October.
In a statement on the Ministry's website, Citizen Protection Minister Nikos Toskas says: "On the case of the Syrian passport found at the scene of the terrorist attack. We announce that the passport holder had passed from Leros on Oct. 3. where he was identified based on EU rules... We do not know if the passport was checked by other countries through which the holder likely passed."
None of the attackers has been publicly identified.
The officials spoke on condition of anonymity because they were not authorized to be publicly named.
The Belgium justice minister says that a "number of" arrests have been made in Brussels relating to the Paris attacks. An official told ABC News that, "Because they are looking for suspects, it was important to conduct operations in Brussels because of the ties they could potentially have here."
Minister Koen Geens told the VRT network that the arrests came after a car with Belgian license plates was seen close to the Bataclan theater in Paris on Friday night, one of the places where victims were killed.
He said it was a rental vehicle and police organized several raids in the St. Jans Molenbeek neighborhood in Brussels on Saturday.
Geens said "there were arrests relating to the search of the vehicle and person who rented it." He said the number of arrests was "more than one."
The Eiffel Tower will be closed indefinitely following the attacks.
PHOTOS: Violence erupts across Paris
A State Department spokesman confirms that Americans are among the injured in the Paris terror attacks.
The department's deputy spokesman, Mark Toner, says Saturday that "the U.S. Embassy in Paris is working around the clock to assist American citizens affected by this tragedy." He would not comment if any were killed.
Hollande, who declared three days of national mourning and raised the nation's security to its highest level, called the carnage "an act of war that was prepared, organized, planned from abroad with internal help."
The Islamic State group's claim of responsibility appeared in Arabic and French in an online statement circulated by IS supporters. It was not immediately possible to confirm the authenticity of the admission, which bore the group's logo and resembled previous verified statements from the group. The statement mocked France's involvement in air attacks on suspected IS bases in Syria and Iraq, noting that France's air power was "of no use to them in the streets and rotten alleys of Paris."
As Hollande addressed the nation, French anti-terror police worked to identify potential accomplices to the attackers, who remained a mystery to the public: their nationalities, their motives, even their exact number. Police said a Syrian passport was recovered from the remains of one suicide bomber outside the stadium.
VIDEO: Six attacks across Paris leave at least 127 dead
Authorities said eight died, seven in suicide bombings, a new terror tactic in France. Police said they shot and killed the other assailant.
Prosecutor's office spokeswoman Agnes Thibault-Lecuivre said authorities couldn't rule out the possibility that other militants involved in the attack remained at large.
The violence raised questions about security for the millions of tourists who come to Paris and for world events routinely hosted in the normally luminous capital, where 1,500 troops were deployed to support police in restoring order and reassuring a frightened populace.
PHOTOS: Tributes to Paris from around the world
French Interior Minister Bernard Cazeneuve announced that all public demonstrations would be banned until Thursday and local governments would have the option to impose nightly curfews. He said police and military reinforcements would be deployed to key public buildings.
Many of Paris' top tourist attractions closed Saturday, including the Eiffel Tower, the Louvre Museum and the Disneyland theme park east of the capital.
Parisians expressed shock, disgust and defiance in equal measure. Hundreds of soccer fans departing the stadium Friday night waved French flags and sang impromptu choruses of the national anthem, "Le Marseillaise." The next morning, hundreds queued outside a hospital near the Bataclan theater, scene of the most appalling violence, to donate blood. As a shrine of flowers expanded along the sidewalk, a lone guitarist sang John Lennon's peace ballad, "Imagine."
Hollande said the attacks meant France would increase its military efforts to crush IS. He said France - which besides bombing suspected IS targets in Syria and Iraq as part of the U.S.-led coalition also has troops fighting militants in Africa - "will be merciless toward the barbarians of Islamic State group."
Reflecting fears in other European capitals of the risk of coordinated or copycat attacks, the British government mounted a meeting of its own emergency COBRA intelligence committee. Italy said it, too, was raising security levels on borders and major public places.
British Prime Minister David Cameron said British citizens were among the casualties in Paris, but he declined to provide specifics. He warned that the threat posed by Islamic State "is evolving."
Friday night's militants launched at least six gun and bomb attacks in rapid succession on apparently indiscriminate civilian targets.
Three suicide bombs targeted spots around the national Stade de France stadium, north of the capital, where Hollande was watching an exhibition soccer match. Fans inside the stadium recoiled at the sound of explosions, but the match continued.
Around the same time, fusillades of bullets shattered the clinking of wine glasses in a trendy Paris neighborhood as gunmen targeted a string of cafes, which were crowded on an unusually balmy November night. At least 37 people were killed, according to Paris Prosecutor Francois Molins.
The attackers next stormed the Bataclan concert hall, which was hosting the American rock band Eagles of Death Metal. They opened fire on the panicked audience and took members hostage. As police closed in, three detonated explosive belts, killing themselves, according to Paris police chief Michel Cadot.
Another attacker detonated a suicide bomb on Boulevard Voltaire, near the music hall, the prosecutor's office said.
Video shot from an apartment balcony and posted on the Le Monde website Saturday captured some of that horror as dozens of people fled from gunfire outside the Bataclan down a passageway to a side street.
At least one person lies writhing on the ground as scores more stream past, some bloodied or limping. The camera pans down the street to reveal more fleeing people dragging two bodies along the ground. A woman and two others can be seen clinging to upper-floor balcony railings in an apparent desperate bid to stay out of the line of fire.
Le Monde said its reporter who filmed the scene from his apartment balcony, Daniel Psenney, was shot in the arm after he stopped filming, when he went downstairs to help someone who had collapsed in the alley.
A tall, sturdy 38-year-old concert-goer named Sylvain collapsed in tears as he recounted the attack, the chaos and his escape during a lull in gunfire.
"I was watching the concert in the pit, in the midst of the mass of the audience. First I heard explosions, and I thought it was firecrackers.
"Very soon I smelled powder, and I understood what was happening. There were shots everywhere, in waves. I lay down on the floor. I saw at least two shooters, but I heard others talk. They cried, 'It's Hollande's fault.' I heard one of the shooters shout, 'Allahu Akbar,'" Sylvain told The Associated Press. He spoke on condition that his full name not be used out of concern for his safety.
He was among dozens of survivors offered counseling and blankets in a municipal building set up as a crisis center.
Jihadis on Twitter immediately praised the attackers and criticized France's military operations against Islamic State extremists.
Hollande declared a state of emergency, announced renewed border checks along frontiers that are normally open under Europe's free-travel zone, and canceled a planned trip to this weekend's G-20 summit in Turkey.
France has been on edge since January, when Islamic extremists attacked the satirical newspaper Charlie Hebdo, which had run cartoons of the Prophet Muhammad, and a kosher grocery. Twenty people died in those attacks, including three shooters.
French authorities are particularly concerned about the threat from hundreds of French Islamic radicals who have traveled to Syria and returned home with skills to mount attacks.
"The big question on everyone's mind is: Were these attackers - if they turn out to be connected to one of the groups in Syria - were they homegrown terrorists or were they returning fighters?" said Brian Michael Jenkins, a terrorism expert and senior adviser to the president of the Washington-based RAND Corporation.
An Air France flight from Amsterdam to Paris has been evacuated at Amsterdam's Schiphol Airport after authorities received a threatening tweet.
Dennis Muller, a Dutch military police spokesman., says Air France flight 1741 was due to take off at 14:45 CET but was evacuated shortly before that.
An Air France spokeswoman said the flight had 85 passengers and six crew members onboard. Police are searching the Airbus A320 now.
Authorities on are alert after at least 127 people died Friday night in gun and bomb attacks in Paris. The Islamic State group has claimed responsibility.
The Foo Fighters are canceling the rest of their European tour following the deadly attacks in Paris.
The band said in a statement Saturday that "it is with profound sadness and heartfelt concern for everyone in Paris that we have been forced to announce the cancellation of the rest of our tour."
Foo Fighters, led by Dave Grohl, were to play at the Accor Hotels Arena in Paris on Monday and in Casalecchio Di Reno, Italy, on Friday; other canceled shows include stops in Turin, Italy; Lyon, France; and Barcelona, Spain.
"In light of this senseless violence, the closing of borders, and international mourning, we can't continue right now. There is no other way to say it," the statement read. "This is crazy and it sucks. Our thoughts and prayers are with everyone who was hurt or who lost a loved one."
French Foreign Minister Laurent Fabius says crucial U.N. conference on fighting climate change will be held in Paris as planned, from Nov. 30 to Dec. 11.
Fabius says the conference "will be held with enhanced security measures, but this is an absolutely indispensable action against climate change." He spoke as foreign ministers met in Vienna to discuss the war in Syria.
So far 127 world leaders have accepted the invitation to come to Paris for the climate conference.
Germany's top security official says the country has ramped up border controls with France after the Paris terror attacks.
Interior Minister Thomas de Maiziere told reporters in Berlin that the move follows a request from France to all of its neighbors to increase controls along their common borders.
De Maiziere said the checks would take place on road, rail and plane connections with France.
In light of the Paris terror attacks, Poland cannot go ahead with EU decisions on immigration and accept refugees without guarantees of security.
Konrad Szymanski, Poland's prospective minister for European affairs, told reporters that Poland "this is a key condition that today was put under a giant question mark in all of Europe."
Szymanski is in Poland's new conservative government that is to be sworn in Monday. The outgoing government agreed to accept 7,000 refugees from Syria and Eritrea over the next two years.
In comments online, Szymanski said Poland must have "full control" of its borders and migration policy.
One of the Paris attackers reportedly came into the EU through Greece last month.
Germany's vice-chancellor has warned against a crackdown on migrants coming to Europe because of the deadly Paris terror attacks.
Sigmar Gabriel says those seeking refuge in Europe shouldn't be made to suffer just because "they come from those regions where terror is being exported to us and to the world."
Chancellor Angela Merkel's deputy's told reporters in Berlin on Saturday that "we stand to protect them too, and to ensure that they don't have to suffer because murderers in France are threatening people and Europe in the name of a religion."
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