The leaders of France and Italy joined Belgium’s Elio Di Rupo on Tuesday to pay homage to the victims of a fatal weekend attack at the Jewish Museum in Brussels.

President Francois Hollande and Prime Minister Matteo Renzi, in Brussels to attend an informal EU summit, met Jewish leaders outside the museum and then bowed their heads in tribute to a rabbi’s prayer.

The three Socialist leaders were joined by European Parliament speaker Martin Schulz, a German Socialist.

Belgium investigators are probing a possible terrorist link in the shooting by a lone gunman that has shocked the world.

The attack — carried out coolly by a “well-prepared” killer, according to police and video images — killed four people.

It was the first for more than 30 years in Belgium and has revived fears of a return of violent anti-Semitism to Europe.

The museum in the heart of Brussels has been closed as investigators continue their inquiry.