PARIS -- An international manhunt had begun for a suspect in the terrorist attacks in Paris, officials said Sunday as the investigation expanded well outside France.
The French National Police identified the suspect as Abdeslam Salah, a 26-year-old man born in the Belgian capital, Brussels. He is one of three brothers believed to have played a role, according to French news reports, though it was not clear what that might have been.
Belgian officials said two of what authorities believe were at least seven assailants had lived in and around Brussels, and information from the Balkans suggested that one of the attackers might have entered Europe as a Syrian asylum seeker.
Another attacker was identified as a man who had been living in France, according to officials in that country.
French police said they found an abandoned car in a suburb of Paris –– just a few miles from where most of the shootings took place –– that might have been used in the attacks.
The discovery of the car, which reportedly contained three automatic rifles, raised the possibility that there were more attackers than the seven who authorities said blew themselves up or were killed by police, and that one or more of them got away.
The militant group Islamic State has claimed responsibility for the assault, which involved six coordinated shootings and explosions at a rock concert venue, several cafes and a soccer stadium at which a match between France and Germany was being played.
In addition to the 129 dead, more than 350 were injured, many of them critically.
Paris remained a city in grief. In response to two major terrorist attacks in less than a year, the government is deploying 3,000 additional troops to secure the French capital, beyond those already stationed here after the massacre in January that targeted the offices of the French satirical magazine Charlie Hebdo and a related attack.
In a sign of how on edge the city is, a spontaneous rally of thousands of Parisians in the Place de la Republique, near where the shootings occurred, descended into chaos Sunday when a car was left running near the square. The people scattered in panic, and police swept through the square with their guns drawn. It turned out to be a false alarm.
Authorities have banned public gatherings. But residents started streaming into the square Sunday afternoon to declare their defiance against the fear the attackers had sought to inspire.
French Interior Minister Bernard Cazeneuve, speaking with his Belgian counterpart Sunday, said the attacks were planned in another country with help from within France. That country is believed to be Belgium, according to U.S. law enforcement officials.
The man identified as one of the dead attackers was Ismael Omar Mostefai, 29, who was reportedly on the authorities' watch list as someone susceptible to radicalization but not yet requiring extensive surveillance.
Mostefai recently had lived in Chartres, a city about 60 miles southwest of Paris.
Mostefai is suspected of being one of three attackers who went on a shooting rampage in the Bataclan theater, in which at least 89 people were killed.
Two of the gunmen blew themselves up with suicide vests; the third was shot by police, French officials said. Authorities identified Mostefai from a fingerprint taken from his severed finger, which was found in the theater.
He was known to police as a small-time criminal whose offenses included driving without a license and insulting behavior toward authority. The daily newspaper Le Monde said Mostefai probably spent the winter of 2013-14 in Syria.
Six of Mostefai's relatives were detained by police for questioning, Le Monde said. One was his brother, who turned himself in for questioning and who told Agence-France Presse that he and Mostefai were estranged.
In Belgium, federal prosecutors announced that two of the dead militants were French nationals who had been living in Brussels and in Molenbeek Saint Jean, a suburb known as a hotbed of Islamic radicalism. A gun-toting man who was overpowered aboard a Paris-bound train in April is believed to have lived there.
The mayor of Molenbeek Saint Jean said Sunday that five people had been arrested there in connection with Friday night's massacre.
Three others were arrested early Saturday in the Brussels area. One of them was reportedly a Frenchman who had rented a car bearing Belgian license plates that was found near the Bataclan concert hall. The car contained parking tickets that allowed authorities to link it to Molenbeek Saint Jean.
French prosecutors said they have determined the identities of two more of Friday's suicide bombers. They did not identify them.
There were also reports that a Syrian passport found near the body of one of the attackers belonged to a man who had entered Europe via Greece last month and then followed the well-worn trail to Northern Europe that hundreds of thousands of migrants have traveled this year.
Greek officials confirmed that the passport holder was registered on the island of Leros, and officials in Serbia and Croatia have also said that the holder of the passport came through their countries.
Whether the passport is authentic or one of the many fake Syrian passports in circulation is unclear.
There have already been calls in some European countries to tighten the flow of asylum seekers as a result of the Paris attacks. But Jean-Claude Juncker, president of the European Commission, rejected the idea.
"Those who organized these attacks, and those who carried them out, are exactly those who the refugees are fleeing," Juncker said in Antalya, Turkey, where he was attending the Group of 20 summit.
(Zavis reported from Los Angeles. Times photojournalist Carolyn Cole contributed to this report.)