Many artists shared their sympathy with France after the attacks that killed at least 129 people in Paris.
French police have released a photo of a fugitive in the Paris attacks, saying the suspect is on the run and too dangerous for anyone outside law enforcement to engage directly.
News of the manhunt came as people gathered across France on Sunday to mark the nation’s second day of mourning following the coordinated attacks, claimed by the Islamic State of Iraq and the Levant (ISIL) group.
Police on Sunday evening identified the man as Salah Abdeslam, a 26-year-old born in Brussels. He was suspected of renting the car that delivered attackers to the Bataclan concert hall where dozens of people were killed.
“Do not intervene,” warns the message issued on Sunday evening.
— Police nationale (@PoliceNationale) November 15, 2015
Abdeslam is thought to be directly involved in Friday’s attacks, which killed 129 people and wounded hundreds in the worst violence in France in decades, French security officials told the AP news agency.
He is one of three brothers believed to be involved in the killings; one was arrested in Belgium and another died in the attack, one official said.
Abdeslam is also under an international arrest warrant issued by Belgium.
Al Jazeera’s Paul Brennan, reporting from Brussels, said security officials have indicated there is an ongoing search operation in the Belgian capital for Abdeslam and other suspects.
“This is a lot of priority being placed on this search,” he said.
In Paris, mourners lit candles and laid flowers on Sunday at the locations of the attacks across the capital, standing in silence as police investigators elsewhere in the country launched a search for the attackers’ accomplices.
Stepping up their hunt for information, authorities found several AK-47 assault rifles in the back of an abandoned SEAT car in an eastern suburb of Paris.
Witnesses said the car, found in Montreuil, was used by attackers at multiple locations on Friday night, the AFP news agency reported.
Earlier, French police identified Omar Ismail Mostefai, a 29-year-old Paris native, as one of the attackers.
Mostefai’s detached finger was found overnight at the Bataclan concert hall, the scene of the bloodiest attack.
The French citizen had been known to police for his alleged links to armed groups but had not been previously linked to violent activities. Police are also holding six of the man’s relatives.
French authorities believe the attacks were planned abroad by ISIL, but have not yet confirmed the identities of others involved.
Belgian authorities, however, said that two of the attackers who died were Frenchmen who had lived in Brussels.
In Belgium, police said they have arrested seven people over their alleged links to the attacks and investigators have found that two cars used in the operation were rented in Belgium, they added.
ISIL purportedly claimed responsibility for the attacks shortly after the incident but has also not revealed the identities of the attackers.
Greek authorities have also confirmed that the holder of a Syrian passport found near the body of a gunman who died in the attacks had registered as a refugee on the island of Leros in October.
Greece identified the man as 25-year-old Ahmad Almohammad, from the northwestern Syrian city of Idlib.
The attacks have intensified debate on Europe’s response to the refugee crisis. Marie Le Pen, the leader of France’s far-right National Front party, has called for a tightening of the country’s borders.
Al Jazeera’s David Chater, reporting from Paris, said security services will be concentrating on how the perpetrators were able to get themselves and their ammunition into France without being noticed.
“The intelligence services will be looking at the blind spots in their system that allowed ISIL to get through their net – exactly where did they get their weapons, how did they get their ammunition, and has the Schengen system made the whole of Western Europe vulnerable.”