PARIS — More than 40 world leaders, including the president of the Palestinian Authority and the prime minister of Israel, marched arm in arm in the vanguard of more than a million people in Paris on Sunday in a somber display of solidarity and defiance after a series of terrorist attacks shook France.
The march, which began shortly after 3 p.m. at the Place de la République, clogged the broad streets as masses of people converged on the center of the capital to show their support after last week’s attacks, which killed 17 people, including three police officers.
A police spokesman said more than 1 million people took part, crowding side streets along the march route. Millions more rallied in other French cities and around the world, including Boston, New York, London, and Madrid — all attacked by extremists — as well as Cairo, Sydney, Stockholm, and Tokyo.
The attacks fanned anxieties about the effectiveness of the state security apparatus and stoked fears about a simmering clash between western European values of freedom of expression and religious extremism.
But they also threw the country into mourning and sadness, evident in the faces of the many who wiped away tears, conveying the strong feelings of grief and despair after a week in which the country had experienced a sense of vulnerability in the face of such abject violence.
Dressed in dark coats, leaders from Europe to Africa, including President François Hollande of France, Chancellor Angela Merkel of Germany, and Prime Minister David Cameron of Britain, marched slowly and resolutely, sending a potent sign that the world was united and would not be intimidated in the face of terrorism. The crowd roared its approval.
Also in the front line of the dignitaries was Israel’s prime minister, Benjamin Netanyahu, accompanied by a bodyguard. In a rare display of unity, the president of the Palestinian Authority, Mahmoud Abbas, stood nearby.
The march served as a national catharsis after the outburst of terror. Families of the victims walked together, grim-faced and, in some cases, sobbing.
Some held the names of their murdered loved ones on a piece of paper and wore white Charlie Hebdo headbands to commemorate the journalists massacred Wednesday at a satirical newspaper that repeatedly lampooned the prophet Muhammad, drawing the rage of Islamic extremists.
The crowd — like the victims of this week’s attacks — included Jews as well as Muslims, some of whom said they were determined to show that the terrorists had not acted in their names.
While the rally was peaceful, a few people were seen holding placards attacking political Islam.
Attorney General Eric H. Holder Jr. was in Paris on Sunday, along with officials from across Europe and North America, to discuss ways to combat and contain terrorism. The United States was represented at the rally and march by its ambassador, Jane Hartley.
The mass rally created a major security headache for the French authorities, two days after security forces killed Amedy Coulibaly, a heavily armed gunman who is suspected of shooting and killing four hostages at a kosher supermarket near Porte de Vincennes in eastern Paris. Two brothers, Saïd and Chérif Kouachi, who are suspected of killing 12 people Wednesday at the offices of Charlie Hebdo, were killed in a separate standoff.
The French government mobilized hundreds of military forces, police, and antiterrorism squads to provide security at the rally. Snipers looked down from rooftops, plainclothes officers mingled among the crowd, and security officers were seen checking sewers for explosives. Numerous subway stops and streets were closed because of the immense throng.
The terror attacks in Paris have stoked deep anxiety among the Jewish community in France, the largest in Europe. It was already reeling from a spate of anti-Semitic attacks, including on synagogues and Jewish shops last year, at the time of an Israeli incursion in Gaza.
On Sunday, Hollande, who has labeled the attack at a kosher supermarket Friday that left four Jewish shoppers dead as a horrific act of anti-Semitism, attended a ceremony with Netanyahu at Grande Synagogue de Paris, to convey his strong support.
In a meeting earlier Sunday with Roger Cukierman, president of the Representative Council of Jewish Institutions in France, Hollande said the government would protect Jewish schools and synagogues with troops if necessary and said it was committed to the security of France’s 500,000 Jews.
But deep fears remain. Cukierman emphasized that French Jews were committed to France, but he said he understood why parents afraid of sending their children to school were emigrating to Israel, where Netanyahu said Sunday they would be welcome with “open arms.”
The trail of terror was extended Sunday when the Paris prosecutor’s office said ballistics tests on bullet casings had connected a gun of Coulibaly’s found in the kosher supermarket to the shooting of a man who was jogging in a Paris suburb Wednesday. The jogger survived.
Coulibaly also is believed to be the man who assassinated a female police officer in Paris on Thursday.
The investigation is a challenge for French law enforcement officials, who already are grappling with the more than 1,000 French citizens who last year went or planned to join jihadists in Syria and Iraq.
The events of the past week appear to confirm fears that some could return to wage attacks on French soil.
The French National Assembly is set to hold a debate and vote Tuesday on whether France should continue participating in US-led airstrikes in Iraq against the Islamic State. France joined the campaign in September, and Islamic State militants have asked their supporters to attack Europeans in retaliation for the strikes.