— A nationwide manhunt was launched Tuesday for the gunman on a motor scooter who methodically killed three French soldiers, three Jewish schoolchildren and a rabbi in a little more than a week in what the chief Paris prosecutor described as crimes of terrorism.

The prosecutor, who is leading the investigation, said all France’s law enforcement resources have been thrown into the effort to track down and apprehend the shooter, who claimed his seven victims at close range. President Nicolas Sarkozy acknowledged that the investigation had produced no solid clues, but he said he was demanding fast results to reassure a population outraged by the killings.

“We are dealing with an extremely determined individual,” the prosecutor, Francois Molins, said at a news conference. “He knows he is being hunted, and he could strike again.”

The intense national concern reflected an instinctive revulsion at seeing three young children and a teacher gunned down in front of a school. But it also grew from the sudden national realization that those slayings and the puzzling killings of the three soldiers appeared to be part of a series, the work of a psychopath with remarkable self-control or acts of terrorism by a politically motivated militant.

Molins said the crimes are being qualified as terrorism but noted that under French law, terrorism can be any crime that is carried out to disrupt the national order and does not have to be linked to a political cause. As a result, he explained, the qualification could cover the case of a hatemonger or racial supremacist as well as that of an Islamist extremist.

Investigators have no clues to guide them in any of those directions, he said. Even the description from a witness that the killer had a video camera hanging around his neck was uncertain, he said, despite the fact that it was cited in radio interviews by Interior Minister Claude Gueant as a possible insight into the gunman’s behavior.

The bodies of the four victims of Monday’s killings at a Jewish school in Toulouse were flown to Paris, meanwhile, in a French military jet. After an airport ceremony presided over by Sarkozy, an Israeli El Al airliner was to carry them to Israel for burial Wednesday according to Jewish rites.

The four — Rabbi Jonathan Sandler, 30, and his two sons, Arieh, 5, and Gabriel, 4, along with Myriam Monsonego, 7 — were dual French-Israeli nationals. Myriam’s father, Yaacov, was the principal at Ozar Hatorah school, and Sandler had come to lend a hand as a religion teacher.

According to accounts from witnesses, the killer rode up to the school on a Yamaha T-Max 530 motor scooter as students gathered for morning classes. He shot Sandler and his sons on the sidewalk outside and then killed the principal’s daughter in the courtyard, all at a range close enough to leave powder burns, Molins said.

Although some witnesses spoke of two weapons, Molins said the victims were all killed by a .45-caliber Colt semiautomatic pistol of the type that formerly was standard issue in the U.S. armed forces. The weapon was the same one used in the killing of a soldier March 11 in Toulouse and in the shooting of three more soldiers — two of whom were killed and one seriously wounded — on March 15 in Montauban, about 30 miles north.

The three dead soldiers were French citizens of North African origin with Arab-sounding names, Molins said, and the wounded soldier was a black citizen from the French Antilles. But there was no indication whether they might have been targeted because of their racial origins, he said.

Like the victims at Ozar Hatorah, the soldiers were shot in the head at close range by a lone gunmen who was described as calm and deliberate.

Witnesses said the killer rode up on the same kind of motor scooter in all three attacks, Molins said, but the scooter used in Montauban was described as black and the one used at the Ozar Hatorah was described as white. Witnesses were unable to provide the license number, he added, but the vehicle was thought to be a scooter that was reported stolen in Toulouse two weeks ago.

To facilitate the manhunt, Sarkozy ordered French security forces to move to “scarlet” alert status, the highest on the scale, for the area of southwestern France around Toulouse and Montauban. It is the first time the scarlet level has been imposed, although for several years the alert status has been at the red level, the next highest, mainly because of fears of terrorist attacks over France’s role in Afghanistan.

The change of status gives police and paramilitary gendarmes broad authority, enabling them, for instance, to demand ID checks without prior suspicions and stop vehicles for searches. Television news programs showed armed officers in Toulouse stopping youths on motor scooters and demanding to see their papers or ordering young women to display the contents of their shopping bags.

Sarkozy, who is a candidate for reelection, visited a middle school in Paris during the minute of silence he had ordered all French schools to observe at 11 a.m. Tuesday. His main adversary, Francois Hollande of the Socialist Party, paid the same type of visit at another school.

Both had suspended their campaigns until Wednesday as part of a national mourning. But politics quickly intruded on the grief. Sarkozy warned children during his visit that such killings could happen anywhere, even at their school. His remark drew immediate criticism from Cecile Duflot of the Greens party, who said children should be reassured and not warned.