French President Francois Hollande and Israeli Prime Minister Benjamin Netanyahu arrived at the Grand Synagogue in Paris for a memorial ceremony in the wake of a series of terrorist attacks across the city, including a siege on a Jewish market by an Islamic extremist.

The Grand Synagogue of Paris shuttered ahead of Shabbat services on Friday night.

The closure marked the first time since World War II that the synagogue, a Paris landmark, was not open for worship on the Sabbath, the Jerusalem Post reported on Friday.

The ceremony at the Grand Synagogue follows a march through the streets of Paris, in which dozens of world leaders including Muslim and Jewish statesmen linked arms leading more than an one million said participants in an unprecedented march under high security in Paris to pay tribute to victims of Islamist terrorist attacks.

Seventeen people, including journalists and police, were killed in three days of violence that began with a shooting attack on the weekly Charlie Hebdo known for its satirical attacks on Islam and other religions as well as politicians. It ended on Friday with a hostage-taking at a Jewish deli in which four hostages were killed.

Overnight, an illuminated sign on the Arc de Triomphe read: “Paris est Charlie” (“Paris is Charlie”).

A video emerged featuring a man resembling the gunman killed in the kosher deli. He pledged allegiance to the Islamic State insurgent group and urged French Muslims to follow his example. A French anti-terrorist police source confirmed it was the killer, Amedy Coulibaly, speaking before the action.

The head of France’s 550,000-strong Jewish community, Roger Cukierman, the largest in Europe, said Hollande had promised that Jewish schools and synagogues would have extra protection, by the army if necessary, after the killings.

France’s Agence Juive, which tracks Jewish emigration, estimates more than 5,000 Jews left France for Israel in 2014, up from 3,300 in 2013, itself a 73 percent increase on 2012.

While there has been widespread solidarity with the victims, there have been dissenting voices. French social media have carried comments from those uneasy with the “Je suis Charlie” slogan interpreted as freedom of expression at all cost. Others suggest there was hypocrisy in world leaders whose countries have repressive media laws attending the march.