For the second time in three weeks, terror struck France, this time with the gruesome beheading of a history teacher in a street in a Paris suburb. The suspected attacker was shot and killed by police.

French President Emmanuel Macron denounced what he called an “Islamist terrorist attack” and urged the nation to stand united against extremism. The teacher had discussed caricatures of Islam’s Prophet Muhammad with his class, authorities said.

The suspect, armed with a knife and an airsoft gun — which fires plastic pellets — was shot dead about 600 meters (yards) from where the male teacher was killed after he failed to respond to orders to put down his arms, and acted in a threatening manner.

The suspect was later identified as an 18-year-old Chechen refugee unknown to intelligence services who posted a grisly claim of responsibility on social media, according to France’s anti-terrorism prosecutor’s office. French anti-terrorism prosecutor Jean-Francois Ricard said an investigation for murder with a suspected terrorist motive had been opened.

Nine other suspects were arrested, including the teen’s grandfather, parents and 17-year-old brother.

Ricard told reporters that the suspect was born in Moscow and had been granted a 10-year residency in France as a refugee in March. His half-sister joined the Islamic State group in Syria in 2014. Ricard didn’t give her name, and it is not clear where she is now.

The prosecutor said a text claiming responsibility and a photograph of the victim were found on the suspect’s phone. He also confirmed that a Twitter account under the name Abdoulakh A belonged to the suspect. It posted a photo of the decapitated head minutes after the attack along with the message “I have executed one of the dogs from hell who dared to put Muhammad down.”

Ricard said the suspect had been seen at the school asking students about the teacher, and the headmaster had received several threatening phone calls.

Macron visited the school where the teacher worked in the town of Conflans-Saint-Honorine and met with staff after the slaying. An Associated Press reporter saw three ambulances at the scene, and heavily armed police surrounding the area and police vans lining leafy nearby streets.

“One of our compatriots was murdered today because he taught … the freedom of expression, the freedom to believe or not believe,” Macron said.

He said the attack shouldn’t divide France because that’s what the extremists want. “We must stand all together as citizens,” he said.

The incident came as Macron’s government works on a bill to address Islamist radicals who authorities claim are creating a parallel society outside the values of the French Republic. France has the largest Muslim population in Western Europe with up to 5 million members, and Islam is the country’s No. 2 religion.

The teacher had received threats after opening a discussion “for a debate” about the caricatures about 10 days ago, the police official told The Associated Press. The parent of a student had filed a complaint against the teacher, another police official said, adding that the suspected killer did not have a child at the school.

It was the second terrorism-related incident since the opening of an ongoing trial for the January 2015 newsroom massacre at the satirical newspaper Charlie Hebdo, which had published caricatures of the prophet of Islam.

As the trial started, the paper republished caricatures of the prophet to underscore the right of freedom of expression. Quickly, a young man from Pakistan was arrested after stabbing two people with a meat cleaver outside the newspaper’s former offices. They did not suffer threatening injuries.The 18-year-old told police he was upset about the publication of the caricatures.

In a video posted recently on social media, a man describing himself as a father at the school said the teacher who was slain had recently shown an offensive image of a man and told students it was “the prophet of the Muslims.” Before showing the images, the teacher asked Muslim children to leave the room because he planned to show something shocking, the man said.

“What was the message he wanted to send these children? … Why does a history teacher behave this way in front of 13-year-olds?” the man asked. He called on other angry parents to contact him, and relay the message.

(AP)