Teacher beheaded in France after showing Mohammed cartoon

France's anti-terror prosecutor said it was investigating the attack, which took place in Conflans Sainte-Honorine

The 18-year-old who beheaded a teacher outside the school in a Paris suburb where he taught had approached pupils in the street and asked them to point out his victim, anti-terrorism prosecutor Jean-Francois Ricard said on Saturday.

Police shot the Moscow-born attacker dead minutes after he murdered 47-year-old history teacher Samuel Paty in broad daylight in the suburb of Conflans-Sainte-Honorine on Friday.

A photograph of the teacher's body, accompanied by a message claiming responsibility posted on Twitter, was found on a phone near the assailant's body. Ricard said the Twitter account belonged to the assailant.

The post was removed swiftly by Twitter, which said it had suspended the account because it violated the company's policy.

Ricard quoted the message as saying: "In the name of Allah the most gracious, the most merciful,... to (President Emmanuel) Macron, leader of the infidels, I have executed one of your hell-hounds who dared to belittle (Prophet) Mohammad."

Paty had earlier this month shown his pupils cartoons of the Prophet Mohammad in a civics class on freedom of expression, angering a number of Muslim parents. Muslims believe that any depiction of the Prophet is blasphemous.

The attacker, of Chechen origin and had been living in the town of Evreux northwest of Paris, was not previously known to the intelligence services, Ricard told a news conference.

The anti-terrorism prosecutor confirmed police were holding nine people in custody in connection with the attack.

The killing shocked the country and carried echoes of an attack five years ago on the offices of satirical magazine Charlie Hebdo. Prime Minister Jean Castex said it bore the hallmarks of Islamist terrorism.

"I want to share with you my total indignation. Secularism, the backbone of the French Republic, was targetted in this vile act," Castex said.

Four relatives of the attacker, including a minor, were detained in the immediate aftermath of the attack, according to police sources. Five more were detained overnight, among them two parents of pupils at the College du Bois d'Aulne where the teacher was employed.

#IAMSAMUEL

A week ago, a man who said his daughter was in Paty's class recorded a video shared on social media in which he branded the teacher a thug and appealed to others to "join forces and say 'stop, don't touch our children'".

It was not clear whether the parent was one of those in police custody. It was also not immediately known if the attacker had seen the video.

Parents of pupils laid flowers at the school gate. Some said their children were distraught.

"(My daughter) is in pieces, terrorised by the violence of such an act. How will I explain to her the unthinkable?" one father wrote on Twitter.

In an outpouring of grief, the hashtag #JeSuisSamuel (I am Samuel) trended on social media, like the #JeSuisCharlie call for solidarity after the attack on Charlie Hebdo in 2015.

Before that attack, Charlie Hebdo had published caricatures of the Prophet Mohammed, unleashing divisions that still cast a pall over French society.

Muslim leaders condemned Friday's killing, which many public figures perceived as an attack on the essence of French statehood and its values of secularism, freedom of worship and freedom of expression.

The litany of deadly attacks by Islamist militants or their sympathisers was devastating for France's Muslim community, Tareq Oubrou, the imam of a Bordeaux mosque, said.

"We are between hammer and anvil," he told France Inter radio. "It attacks the Republic, society, peace and the very essence of religion, which is about togetherness."