A manhunt is on in France for the gunman who murdered three young children and a rabbi at a Jewish school Monday in Toulouse.

The government has raised its terror alert in southwestern France to “scarlet” — its highest level and just one notch below a state of emergency.

Security has been upgraded at Jewish and Muslim schools and guards are posted outside religious sites.

President Nicolas Sarkozy and Prime Minister Francois Fillon attended a memorial service at a Paris synagogue Monday night while thousands of citizens marched in silence in the French capital.

Mr. Sarkozy has suspended his re-election campaign. Socialist presidential candidate Francois Hollande and right-wing contender Marine Le Pen have also temporarily stopped their presidential campaigns.

President Sarkozy has called for a moment of silence in all French schools Tuesday morning. He said the anti-Semitic motivation in the attack is obvious.

Witnesses say the gunman, his face disguised by a helmet, opened fire at the Ozar Hatorah school just before morning classes Monday. The victims are three children — ages four, five, and seven — and a rabbi. The shooter fled on a motorcycle.

French police say the same same gun was used to kill three French soldiers of African and French Caribbean origin last week, also in Toulouse and a nearby town. Investigators suspect racism was behind the attack.

World reaction to Monday's school shooting has been one of outrage and horror. The rabbi and three children were dual French and Israeli citizens. Israeli Prime Minister Benjamin Netanyahu condemned the shooting as a “despicable murder” and said Israel will do everything it can to help French authorities find the killer.

The White House said it is deeply saddened by the attack and called it an “unprovoked and outrageous act of violence.”

U.N. Secretary-General Ban Ki-moon also condemned the shooting “in the strong possible terms” and expressed condolences to the victims' families, the Jewish community, and the French people.

France is home to at least a half-million Jews who represent Europe's largest Jewish community. The Toulouse shooting was the deadliest attack on that community since the early 1980s.

A French organization that monitors anti-Semitism says 389 incidents were recorded last year, ranging from vandalism to violence. The figure reported by the Protection Service for the Jewish Community (SPCJ) marked a decline from 466 anti-Semitic acts in 2010.

The Anti-Defamation League, a U.S.-based rights group, told VOA that Toulouse has seen several “troubling” anti-Semitic incidents in recent years, including the ramming of a burning car into the front of a synagogue while a rabbi and children were inside in 2009. Vandals broke into another local synagogue in 2010 and scrawled the words “dirty Jews.”

ADL's director of international affairs Michael Salberg said those incidents have left the French Jewish community feeling insecure. He said the response of French leaders and law enforcement to Monday's attack was “very positive,” but he said France must do more to prevent additional tragedies. Salberg urged French authorities to be on “constant alert for danger and to keep that level of vigilance high.”