French security forces have been searching for a possible eighth attacker in Friday's terror attacks that killed at least 129, officials said on Sunday.
Sources said investigators were looking for Salah Abdeslam, whose brother Ibrahim was believed to be one of the other attackers. Both were French nationals living in Belgium.
Another terrorist was named as Bilal Hadfi, also a Belgian resident, according to the Washington Post.
French police earlier identified one of the assailants in the coordinated attacks in Paris as Ismael Omar Mostefai, a 29-year- old French national, and seven of his relatives were questioned.
New evidence that emerged on Sunday suggested that planning of the attack went beyond France's borders. Three of the seven suicide bombers killed in the Paris attacks were French citizens, as was at least one of the seven other people arrested in neighboring Belgium suspected of links to the attacks.
The French National Police's Twitter account called for the public to help find the missing suspect, naming him as 26-year-old Abdeslam Salah and warning that he was "dangerous".
Born September 15, 1989 in Brussels, Belgium, Salah measures 1.75m and has brown eyes, said the announcement.
Four French officials acknowledged on Sunday that police had Abdeslam in their grasp when they stopped a car carrying him and two other men near the Belgian border early Saturday. By then, hours had passed since authorities identified Abdeslam as the renter of a Volkswagen Polo that carried hostage takers to the Paris theater where so many were killed.
A French police official confirmed that Mostefai had been identified by a skin sample had been living in a Paris suburb. A Belgian official said two of the seven suicide bombers were French men living in Brussels, and among those arrested was another French citizen living in the Belgian capital. Seven attackers died in Friday's attacks. In a sign that at least one gunman might have escaped, a source close to the investigation said a Seat car believed to have been used by the attackers had been found in the eastern Paris suburb of Montreuil with three Kalashnikov rifles inside.
Authorities had a dossier on Mostefai that marked him as a potential Islamist militant. He also had previous arrest records and had been sentenced eight times for petty crimes, according to French newspaper Le Monde.
Mostefai was one of the gunmen who blew himself up in a Paris concert hall where most of the 129 deaths from the attacks late on Friday took place.
His father, a brother and five other people are being held for questioning, several French media reported on Sunday, as the hunt continued for others involved in the shootings.
The reports said searches were also being conducted in the relatives' homes in the northeastern Aube region and in Essonne, south of Paris.
A Frenchman who thought to have hired another car used in the attacks was stopped at the Belgian border on Saturday morning, along with two other people, Molins said.
Molins said investigators believed three coordinated teams had carried out the wave of attacks across Paris. They were the worst in Europe since the Madrid train bombings of 2004, in which Islamists killed 191 people.
Friday's attacks were described as an "act of war" by President Francois Hollande .
The bloodshed came as France, a founder member of the US-led coalition waging air strikes against Islamic State in Iraq and Syria, was already on high alert for terrorist attacks.
Israel helps France with intelligence
Meanwhile, Israel said on Sunday its spy services were helping France investigate the attacks, and Israeli media suggested that intelligence being provided drew on surveillance of militant groups in Syria and Iraq.
Prime Minister Benjamin Netanyahu said he had ordered full cooperation with French and other European authorities trying to identify the perpetrators and prevent further attacks.
Israel's Army Radio said electronic surveillance of Syria and Iraq - where Islamic State insurgents have conquered swathes of territory - may have yielded intelligence on the organization of the Paris attacks.
According to Channel Two, Israel had no advance warning of the Paris attacks but within hours of the assaults gave France details on some of the Islamic State militants believed to have carried them out.
Citing an unnamed senior Israeli official, Channel Two said Israel saw a "clear operational link" between the Paris attacks, Thursday's Beirut suicide bombings and the Oct. 31 downing of a Russian airliner in the Egyptian Sinai.
The Syrian passport
The owner of a passport found near the body of one passed through a migrant corridor known for its lax controls and ease in obtaining transit documents as a flood of asylum-seekers surges toward Western Europe.
The Syrian passport was registered in October in Greece, Serbia and Croatia, three of the countries on the corridor crossing the Balkans. The owner was allowed to proceed because he passed what is essentially the only test in place – he had no international arrest warrant against him, police in the states said Sunday.
It was not clear whether the passport was real or fake, or whether it belonged to the suicide bomber. But trafficking in fake Syrian passports has increased as hundreds of thousands of people fleeing war and poverty try to get refugee status, the chief of the European Union border agency Frontex has said.
While the passport immediately raised concerns that the bomber was a refugee who recently arrived in Europe, Germany's defense minister has pushed back against the idea that terrorists are entering Europe as refugees.
Ursula von der Leyen said Sunday that linking Europe's migrant crisis to the threat of terrorism would be wrong.
She says that "terrorism is so well organized that it doesn't have to risk the arduous refugee routes, and the sometimes life-threatening crossings at sea."
Muslim world condemns attacks
Condemnations of the Paris attacks poured in from across the Muslim world on Saturday and Sunday, with Jordan, the Gulf states, Iran, Hezbollah and the Syrian regime expressing condolences over the deaths in the French capital.
The secretary general of the world's largest body of Muslim nations, the Organization of Islamic Cooperation, has condemned the terrorist attacks in Paris and has expressed the organization's "unwavering solidary and support to France."
From the Saudi-based headquarters of the 57-nation bloc, OIC chief Iyad Madani said the organization firmly rejects any terrorist acts that violate the right to life and that seek to undermine the "values of freedom and equality that France has consistently promoted."
Hassan Nasrallah, chief of Lebanon's powerful Shiite Muslim movement Hezbollah, strongly condemned on Saturday the Islamic State's attacks in Paris that killed at least 129 people and wounded more than 300.
"We, Hezbollah, express our strong condemnation and denunciation of the terrorist attack by the criminals of Daesh in Paris," he said in a televised address, using the Arabic acronym for the jihadist group.
Expressing his solidarity with the French people, he said the Middle East was also suffering "the earthquake" of jihadist groups.
Nasrallah was speaking on Hezbollah's Al-Manar television channel two days after twin ISIS suicide bombings in a southern Beirut stronghold of the group killed more than 40 people.
"There is no future for Daesh. Not in war and not in peace," he said.
Syrian President Bashar Assad said: "The French people are suffering from the same thing we have been for the last five years."
The al-Alam newspaper in Iran commented on social media that "Wahabi terror has hit Paris," referring to the fundamentalist strain of Islam that originated in Saudi Arabia.
Al-Arabi al-Jadeed, an Arabic newspaper published in London, featured a cartoon with a suicide bomber inside the Eiffel Tower wearing a suicide belt, about to blow himself up.
A cartoon published in Saudi Arabia, meanwhile, showed a French flag flying from the Eiffel Tower, with the red part of the Tricolore dripping blood.
Itay Blumenthal, Rachel Cadars, Roi Kais and Liad Osmo contributed to this report.