Police have launched one of the biggest manhunts in French history for the gunman who killed four people at a Jewish school in Toulouse, including three children.

More shocking details of the shooting at the Ozar Hatorah private Jewish secondary school in northeast Toulouse have emerged.

Witnesses said a man whom they described as "determined and athletic" arrived on a dark scooter and headed towards the school gate without removing his helmet.

He then opened fire, shooting at whoever and whatever was in his path.

According to reports, Jonathan Sandler, a 30-year-old rabbi and religious education teacher who recently joined the school, was the first to be shot before the gunman turned fire on his two sons, Gabriel, three, and Arye, six.

Sandler was waiting with his sons for a minibus to take them to their nursery school. All three are dead.

After the 9mm weapon he was using jammed, the attacker switched to a .45 calibre gun and continued his shooting spree.

He then shot a 17-year-old boy who is now fighting for his life in hospital.

Witnesses spoke of their horror and shock when the killer cornered eight-year-old Miriam, the daughter of school principal Yaacov Monsonego, put a gun to her head and fired.

"You see a man park his motorcycle, start to shoot, enter the school grounds and chase children to catch one and shoot a bullet into her head. It's unbearable to watch. He was looking to kill,", Nicola Yardeni, regional president of the French Jewish organisation CRIF (Conseil Représentatif des Institutions Juives de France), said after viewing CCTV footage of the shootings from surveillance cameras.

"He was calm and determined. In cold blood he assassinated them as if he was killing animals," Yardeni added.

The man then left the school, mounted his scooter and sped off.

Interior minister Claude Gueant also relayed information from a witness who said that the gunman was wearing a video camera around his neck.

Gueant said the attacker "was wearing on his bloody chest a kind of filming apparatus".

When asked whether the gunman had recorded the scene, he replied: "We can imagine that."

The minister added that police were now combing the internet trying to establish whether a video of the incident has been posted online.

Was Killer Neo-Nazi Military Man?

As the hunt for the fugitive gets under way, there has been speculation that the crime may be linked to two similar attacks on French soldiers, which took place last week in the same part of France. The killer also used a dark scooter.

A soldier was shot dead in Toulouse and three days later another two soldiers were shot dead in Montauban, while another was left wounded.

The three soldiers who died in the attacks were of north African descent and the injured serviceman was from Guadeloupe in the Caribbean, prompting observers to say that all three attacks appear to have been motivated by racism.

In all three incidents, the killer also remained determined, calm and showed great precision.

French media reports suggest investigators suspect three former soldiers, who were sacked from their regiment in 2008 for "neo-Nazi" activities. The soldiers who were killed were part of the same logistics regiment.

Three soldiers were kicked out of an elite parachute regime four years ago after they were pictured making Nazi salutes in front of a swastika. One or more of them may be behind the shootings.

Police sources say investigators think the criminal is a military man, but they are also considering other possibilities, such as a fundamentalist Islamic group.

The killings occurred at a time when there are risking tensions over immigrants and the state's immigration policies as the country gears up for the presidential elections, which will start in April.

President Nicolas Sarkozy was criticised for saying there are "too many immigrants in France". Marine Le Pen, leader of the far-right Front National, has also based her electoral campaign on immigration laws and the negative impact of immigrant culture and religion on France.