PARIS - French police questioned on Sunday relatives of one of the suicide attackers who brought carnage to Paris as a row over Europe's refugee crisis re-ignited, with conservatives demanding an end to "the days of uncontrolled immigration."
Paris prosecutor Francois Molins told reporters that three jihadist cells staged co-ordinated hits on Friday night at bars, a concert hall and soccer stadium, killing 129 people and injuring 352, including 99 who were in a serious condition.
Prosecutors have said the slaughter - claimed by Islamic State as revenge for French military action in Syria and Iraq - appeared to involve a multinational team with links to the Middle East, Belgium and possibly Germany as well as home-grown French roots.
Belgian police arrested three people on Saturday in raids in a poor, immigrant quarter of Brussels as they pursued emerging links between the Paris attacks and an Islamist bastion in France's northern neighbor.
Further evidence emerged that at least one of the attackers had traveled through Europe alongside Syrian refugees, seeking asylum in Serbia. But with the European Union deeply split over the migrant crisis, European Commission head Jean-Claude Juncker stressed the attacker was not a refugee but a criminal.
Museums and theaters remained closed in Paris for a second day Sunday, with hundreds of soldiers and police patrolling the streets and metro stations after French President Francois Hollande declared a state of emergency.
Seven gunmen, all of whom were wearing suicide vests packed with explosives, died in the multiple assaults. The first to be identified was named as Ismael Omar Mostefai, a 29-year-old who lived in the city of Chartres, southwest of Paris.
French media said he was French-born and of Algerian descent. Molins said the man had a security file for Islamist radicalization, adding that he had a criminal record but had never spent time in jail. He was identified through tests on his severed finger.
A judicial source said Mostefai's father and brother had been taken in for questioning, along with other people believed to be close to him.
Another source said police had found a car in a suburb east of Paris that was believed to have been used in the assault, suggesting that at least one of the attackers had escaped.
At least one of the other attackers appears to have followed the route taken by hundreds of thousands of asylum seekers who have crossed by boat from Turkey to the Greek islands, before heading through the Balkans to EU countries to the north, mainly Germany and Sweden.
In Belgrade, the Serbian government said the holder of a Syrian passport found near the body of one of the gunmen had passed through the country last month where he sought asylum.
The Interior Ministry said the man, whom it identified only by the initials A.A., had been registered at Serbia's Presevo border crossing with Macedonia on Oct. 7.
It said his details were the same as those of a man who had registered in Greece on Oct. 3. Greek authorities said on Saturday that the passport matched one used by someone who had landed on the island of Leros. They believe that another of the assailants may also have passed through Greece from Turkey alongside Syrian refugees fleeing the country's civil war.
The attacks have reignited a row within the EU on how to handle the flood of asylum seekers from Syria and other countries in the Middle East, Africa and Asia.
Top Polish and Slovak officials have poured cold water on an EU plan to relocate asylum seekers across the bloc, saying the violence underlined the concerns of Europeans about taking in Muslim refugees.
But Juncker said EU states should not give in to base reactions. "The one responsible for the attacks in Paris... he is a criminal and not a refugee and not an asylum seeker," he told a news conference on the sidelines of a G20 summit of world leaders in the Turkish coastal province of Antalya.
"I would invite those in Europe who try to change the migration agenda we have adopted - I would like to remind them to be serious about this and not to give in to these basic reactions," Juncker added.
Nevertheless, Bavarian allies of German Chancellor Angela Merkel raised the pressure to reverse her "open-door" refugee policy, saying the attacks underlined the need for tougher measures to control the influx of migrants.
"The days of uncontrolled immigration and illegal entry can't continue just like that. Paris changes everything," said Markus Soeder, the finance minister of Bavaria - the state where most asylum seekers have arrived in Germany.
Speaking to Welt am Sonntag newspaper, Soeder stressed his Bavarian conservative party still supported the chancellor, but added: "It would be good if Angela Merkel acknowledged that the opening of the border for an unlimited period of time was a mistake."
In Vienna, Iraqi Foreign Minister Ibrahim al-Jaafari said his country's intelligence services had shared information they had which indicated that France, the United States and Iran were among countries being targeted for attack.
Jaafari said from the sidelines of talks in the Austrian capital on ending the war in Syria that the countries had been informed but he did not elaborate.
At the G20 summit, President Barack Obama described the killings in Paris as an attack on the civilized world and said the United States would work with France to hunt down those responsible.
French Prime Minister Manuel Valls said his country was at war. "We have been hit by an act of war, organized methodically by a terrorist, jihadist army," he told TF1 television on Saturday night.
"Because we are at war we will take exceptional measures. We will act and we will hit them. We will hit this enemy to destroy them, obviously in France and Europe ... but also in Syria and Iraq," he said. "We will win."
France was the first European state to join U.S. air strikes against Islamic State targets in Iraq in September 2014, while a year later it extended its air strikes to Syria.
It had already scheduled to send an aircraft carrier to the region later this month.
The names of the first victims have started to filter out on social media, many of them young people who were out enjoying themselves on a Friday night. The dead included one U.S. citizen, one Swede, one Briton, one German, two Belgians, two Romanians and two Mexicans, their governments said.
In the worst carnage, three gunmen systematically killed at least 89 people at a rock concert by an American band at the Bataclan theater before detonating explosive belts as anti-terrorist commandos launched an assault.
Members of the U2 rock group laid flowers at a makeshift memorial near the hall, including its singer, anti-poverty campaigner Bono. The Irish band had been due to perform in Paris on Saturday, but canceled the concert following the attacks.
It was the deadliest attack in France since World War II and the worst such assault in Europe since the Madrid train bombings of 2004, in which Islamists killed 191 people.
Quoting an unnamed senior official, Israeli television said Israel's spy services saw a "clear operational link" between the Paris mayhem, suicide bombings in Beirut on Thursday, which killed 43, and the Oct. 31 downing of a Russian airliner in the Egyptian Sinai, where 224 people died.
France had been on high alert since Islamist gunmen attacked the satirical weekly Charlie Hebdo and a kosher supermarket in January, killing 18 people.
Those attacks briefly united France in defense of freedom of speech, with a mass demonstration of more than a million people. But that unity has since broken down, with far-right populist Marine Le Pen gaining on both mainstream parties by blaming France's security problems on immigration and Islam.