PARIS – Thousands of French troops deployed around Paris on Sunday and tourist sites stood shuttered in one of the most visited cities on Earth while investigators questioned the relatives of a suspected suicide bomber involved in the country's deadliest violence since World War II.
The Islamic State group claimed responsibility for Friday's attacks on a stadium, a concert hall and Paris cafes that left 129 people dead and over 350 wounded, 99 of them seriously.
The attack had global impact. Security was heightened across France, across Europe's normally open borders, even across the ocean to New York, and how to respond to the Paris attacks became a key point among U.S. Democratic presidential hopefuls at a debate Saturday night.
Countries around the world doused their national buildings in the French colors of blue, white and red to honor the victims — or, like the Eiffel Tower and New York's Empire State Building, went dark to express their sorrow.
Paris prosecutor Francois Molins said three groups of attackers, including seven suicide bombers wearing identical vests containing the explosive TATP, carried out the attacks that began as Parisians enjoyed a night out Friday.
The tentacles of the investigation reach well beyond France. The attackers mentioned Syria and Iraq, the Paris prosecutor said. Authorities in Belgium arrested three people in raids linked to the Paris attacks. A Syrian passport found next to the body of a man who attacked France's national stadium appeared to suggest he passed through Greece into the European Union last month.
With 3,000 extra troops being mobilized to protect Paris, French authorities labored Sunday to identify the suicide bombers and hunt potential accomplices still at large. French authorities are particularly concerned about the threat from hundreds of French Islamic radicals known to have spent time in Syria.
Details about one attacker began to emerge: 29-year-old Frenchman Ismael Mostefai, who had a record of petty crime and had been flagged in 2010 for ties to Islamic radicalism. He was identified from fingerprints found on a finger amid the bloody carnage from a Paris concert hall, the Paris prosecutor said. A judicial official and lawmaker Jean-Pierre Gorges confirmed his identity.
Police detained his father, brother and other relatives Saturday night, and they were still being questioned Sunday, the judicial official said, on condition of anonymity because the investigation is ongoing.
Officials in Greece, meanwhile, said the passport's owner entered Oct. 3 through Leros, one of the eastern Aegean islands that tens of thousands of people fleeing war and poverty have been using as a gateway into Europe.
Belgian authorities raided a Brussels neighborhood and arrested three people near its border with France after a car with Belgian license plates was seen close to Paris' Bataclan theater, where at least 89 people died in a hailstorm of bullets.
A French judicial official says a Seat car with suspected links to gun attacks on Paris bars and restaurants was found by police in Montreuil, a suburb 6 kilometers (nearly 4 miles) east of the French capital. The official spoke Sunday on condition of anonymity because she was not publicly authorized to speak.
In a statement claiming responsibility, the Islamic State group called Paris "the capital of prostitution and obscenity" and mocked France's air attacks on suspected IS targets in Syria and Iraq.
French President Francois Hollande vowed that France would wage "merciless" war on the Islamic State group and declared three days of national mourning that began Sunday. He raised the nation's security to its highest level and banned all public demonstrations until Thursday.
The president said France, already bombing Islamic State targets in a U.S.-led coalition, would increase its military efforts to crush IS.
Struggling to keep his country calm and united after an exceptionally violent year, Hollande was meeting Sunday with opposition leaders — conservative rival and former President Nicolas Sarkozy as well as increasingly popular far-right leader Marine Le Pen, who has used the attacks on Paris to advance her anti-immigrant agenda.
The entire nation was enveloped in mourning. Flags were lowered and Notre Dame Cathedral — closed to tourists like many Paris sites — planned a special church service Sunday for families of the victims. Well-wishers heaped flowers and notes on a monument to the dead in the neighborhood where teams of attackers sprayed gunfire on cafe diners and concert-goers.
Parisian Quentin Bongard said he left one of the targeted cafes after a fight with his girlfriend just moments before the attacks.
"Those are all places that I go often to," he said, still shaken with emotion. "We just want to come here, bring flowers, because we don't want to be terrorized ... but it is frightening."
Yet even in their grief, residents were defiant about the lifestyle that has made their city a world treasure. Olivier Bas was among several hundred who gathered late Saturday at the site of the Bataclan concert hall massacre. Although Paris was quiet and jittery, Bas intended to go out for a drink — "to show that they won't win."
The Islamic State group has claimed responsibility for several recent attacks. On Thursday, twin suicide bombings in Beirut killed at least 43 people and wounded more than 200, and 26 people died Friday in Baghdad in a suicide blast and a roadside bombing that targeted Shiites. The militant group also said it bombed a Russian plane that crashed in Egypt's Sinai Peninsula on Oct. 31, killing 224 people.
French Muslim groups firmly denounced all the attacks. Some are concerned about a backlash against France's overwhelmingly moderate Muslim community.
Elsewhere in Europe, refugees fleeing to the continent by the tens of thousands feared that the Paris attacks will prompt EU nations to throw up even more border fences and other obstacles to their quest to start a new life.
"This is the same act of terrorism like they act in Syria or Iraq," said Zebar Akram, a 29-year-old Iraqi refugee trudging through Slovenia, said of the IS attacks on Paris.
Refugees now "will be considered as probable attackers," said Abdul Selam, a 31-year-old from Syria.
Associated Press writers Greg Keller, Lori Hinnant, Raphael Satter, Thomas Adamson and John Leicester in Paris; Maamoun Youssef in Cairo, John-Thor Dahlburg in Brussels, Jill Lawless in London and Shawn Pogatchnik in Dublin contributed to this report.