The beheading of teacher Samuel Paty, who had shown cartoons of the prophet Mohammed to pupils in class, has left France in shock.
Here is what we know about the killing on Friday afternoon outside Paris:
At 5:11 pm, police officers in Conflans-Sainte-Honorine northwest of Paris were notified by colleagues in the nearby town of Eragny that the body of a decapitated man had been discovered on a road, according to anti-terror prosecutor Jean-Francois Ricard.
When police arrived at the scene, a man fired five shots from a handgun in their direction and tried to stab the officers as they closed in, Ricard said.
The man was shot by police nine times and later died of his injuries. He was armed with a knife and an airgun, and a second bloody 35-centimetre (14-inch) knife was discovered near the victim's body.
Sources close to the investigation have said that the assailant shouted "Allahu Akbar" before the police opened fire.
Who was the victim?
The teacher was Samuel Paty, 47, who taught history and geography in a quiet suburban district of Conflans-Sainte-Honorine and was on his way home from school when he was attacked.
At the beginning of October, he taught a class on freedom of expression for which he showed pupils caricatures of the prophet Mohammed.
Teachers and pupils have praised his skills as a teacher while the French presidency has said a day of national hommage will be organised to pay tribute to Paty.
Who was the perpetrator?
Suspected perpetrator Abdullakh Anzorov was an 18-year-old born in Moscow but originally from Russia's southern region of Chechnya.
He had been granted refugee status in France and received a 10-year residency permit earlier this year, Ricard said.
He was not known to the intelligence services and had no convictions but had been in trouble for inflicting damage on public property and violence while still a minor, he said.
Anzorov lived in the Normandy town of Evreux, and his neighbours described him as "discreet" and "immersed in religion" for the past three years.
A message claiming the attack with a gruesome accompanying photo was published on a Twitter account confirmed to have belonged to Anzorov, in which he described President Emmanuel Macron as "the leader of the infidels" and said he wanted revenge on those "who dared to belittle Mohammed", said Ricard.
Why was the teacher targeted?
According to Ricard, a father of one of the pupils at the school had embarked on a campaign to have the teacher dismissed when he found out about the cartoons.
He spoke to the head of the school and published calls on social media attacking the teacher and insisting it is time to "say stop" to such behaviour.
According to Ricard, initial evidence suggests the perpetrator loitered outside the school on Friday afternoon and asked pupils where he could find Paty.
There is so far no suggestion of any link between the perpetrator and the school.
Who has been arrested?
A total of 11 people have been detained for questioning, including the father who complained about the teacher's class.
Ricard said the half-sister of the father had joined Islamic State (IS) jihadists in Syria in 2014 and is already the subject of an arrest warrant.
Another man who took part in videos posted by the father calling for the dismissal of the teacher has also been detained, along with his wife. The man had accompanied the father to the school to complain about the teacher.
Four of the suspect's relatives -- his younger brother, grandfather and parents -- were also detained for questioning.
Four people who were in contact with the attacker are also in custody.