French investigators fear a gunman who has killed three soldiers and four Jews, including three children, in cold-blooded attacks may strike again, the head of the inquiry warned, yesterday.

Someone very cold, determined, very in control of himself, very cruel

Francois Molins, who as chief Paris prosecutor oversees counter-terrorism investigations, said the unidentified gunman knows that he is being hunted and warned that he is “likely to act again.”

“All the dead victims received a bullet wound fired at point blank range at the level of the head,” Mr Molins said, explaining that powder burns showed the muzzle of the gun was touching the victims.

Meanwhile, police were scouring the internet in search of potentially grim footage after witnesses said the gunman was wearing a video camera when he murdered the Jewish school children in the southern city of Toulouse.

News that the mystery serial killer may have recorded his crimes came as France was struggling to come to terms with the tragedy.

School pupils across the country joined public employees and lawmakers to observe a minute of silence for the victims of the gunman’s latest attack, and the country’s presidential race was effectively put on hold.

Mr Molins said police believe the scooter-riding gunman was responsible for the murder of an off-duty paratrooper on March 11, of two of his comrades on Thursday and of a rabbi and three Jewish children in Monday’s school attack.

Officials have said the same gun and make of scooter was used in all three attacks and noted that the three attacks were carried out at precise four-day intervals.

Mr Molins said the attacks had been classified as terrorism because they “gravely disturbed public order by intimidation or terror” adding that the killings could be “racist and anti-Semitic but still also terrorist.”

President Nicolas Sarkozy paid silent homage to the victims at a school in Paris close to the city’s Holocaust memorial, and afterwards admitted that authorities had as yet no clue as to the identity of the killer.

“Anti-Semitism is obvious. The Jewish school attack was an anti-Semitic crime,” Mr Sarkozy told reporters at the Paris school after meeting children.

“But the soldiers? Was it because they were back from Afghanistan? Was it because they were from minorities? We don’t know,” he said. “We must be very cautious until we have arrested someone.”

The three soldiers who died were French citizens of North African origin, while another who was critically wounded in the attack was black and from the French West Indies.

On Monday, the gunman launched a controlled but vicious attack on a group of parents and children outside the Ozar Hatorah school.

Teacher Jonathan Sandler, 30, and his two sons Arieh, 5, and Gabriel, 4, were shot dead in the street. The killer then ran onto the grounds and shot Miriam Monsonego, the seven-year-old daughter of the school director.

“When you grab a little girl to put a bullet in her head, without leaving her any chance, you’re a monster. An anti-Semitic monster, but first of all a monster,” Mr Sarkozy said.

The bodies of the four victims were yesterday flown to Paris with their families, where they were to be joined by Foreign Minister Alain Juppe en route to Israel for burial in Jerusalem, today.

Mr Sarkozy paid his respects to the bodies as they lay in Charles de Gaulle airport.

Interior Minister Claude Gueant said the shooter may have recorded his crime with a sports video camera witnesses saw strapped to his chest and that he could be planning to put the footage on the internet.

Mr Molins however said there was no “certainty” that the killer had a camera, adding it was a “hypothesis” based on sometimes confused witness reports.

During a tour of Toulouse to check beefed up security arrangements in the southwestern city, Mr Gueant said the video clue would bolster what little information police are thought to have about the killer.

He appears to be “someone who is very cold, very determined, very in control of himself, very cruel”.

Norwegian extremist Anders Behring Breivik, who last July went on a shooting spree that killed 77 people, mostly children, advised anyone wanting to carry out copycat killings to film their attack using such a camera.

With apparently few clues to go on, police were downplaying suspicions hanging over three soldiers recently sacked for expressing neo-Nazi views, a source close to the probe said.

Two of the paratroopers killed last week were from the 17th Parachute Engineering Regiment (17e RGP), from where three soldiers were drummed out after an incident in 2008 when they staged a neo-Nazi demonstration.