The US ambassador to Paris on Monday, March 19 condemned as "horrific" an attack by a gunman who opened fire at a Jewish school in southwestern France, killing four people, AFP reported.

"I strongly condemn these killings, along with the murders of French soldiers that occurred last week in Toulouse and Montauban," Charles Rivkin said in a statement.

President Nicolas Sarkozy declared the murders a "national tragedy" as anti-terror police probed the third fatal shooting involving a motorcyclist wielding a large calibre pistol in the Toulouse region in recent days.

Police launched a major manhunt last week after the killing of three paratroopers of Arab origin and the wounding of another from the Caribbean in two separate incidents.