A man who killed two women with a knife at Marseille's Saint Charles railway station on Sunday was shot dead by soldiers, as the Islamic State terrorist group appeared to claim responsibility for the attack.
But there have also been numerous smaller attacks on police officers, soldiers or members of the public since then, sometimes carried out by people with severe psychological problems.
He added that two victims were stabbed to death.
France has been the Western country hardest hit by Islamic terror attacks in recent years.
"There's something to the cluster effect, especially with social media, as someone sees this reverberate from what one person did and follow suit", Clarke told the Herald.
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Some diplomats heard various loud noises or felt vibrations during the attacks , others heard nothing but reported symptoms later. Since the FBI took over the investigations, there has been no word from the agency, on its preliminary findings.
The incident is being treated as a terror attack and has been handed over to a special prosecutor in Paris, the prosecutor's office told CNN. No further details were immediately given, including the motive for the attack.
French authorities are not considering the incident a terrorist attack, the AP reported.
France is a leading partner in the US-led global coalition fighting IS in Iraq and Syria, where the jihadists are being driven back.
The attack came two weeks after four young American women were attacked with acid at the same station.
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Interior Minister Gerard Collomb, who went to Marseille to meet with local authorities and troops on the scene, said police had video showing the man attacking a woman and running away, then coming back and attacking a second woman.
The deadliest of all the attacks came in November that year when terrorists brutalized the capital city of Paris, killing more than 120.
The investigation is now underway to ensure the authenticity of the ID submitted in Lyon, which the Marseille suspected attacker didn't have on him at the time of the attack.
President Emmanuel Macron said on Twitter he was "disgusted by this barbaric act" and praised the calmness and efficiency of security forces.
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