PARIS (AFP) -- France effectively put its election campaign on hold Monday after a gunman killed three children and a teacher at a Jewish school, with top candidates condemning the attack and rushing to the scene.

President Nicolas Sarkozy and the Socialist frontrunner in the presidential race, Francois Hollande, both cancelled campaign events and headed for the southwestern city of Toulouse.

Calling the shooting a "national tragedy", Sarkozy cancelled a campaign meeting in Paris and flew to Toulouse with Education Minister Luc Chatel and Jewish community leaders.

Hollande also said he was heading to the city to show his "solidarity with the families and France's Jewish community."

"This act, whose anti-Semitic nature is as obvious as it is despicable, hits what families hold most dear, their children, and plunges the entire nation into mourning," Hollande said in a statement.

His spokesman, Benoit Hamon, said the campaign had been suspended to "honour the memories" of the victims.