France's government on Tuesday denied any links between three attacks in as many days, including two nearly identical rampages by drivers who plowed into holiday crowds, but announced plans to further raise security in public spaces.

The prime minister said the attacks were unrelated to terrorism. Lamenting "the ravages of propaganda on fragile minds," he urged France to remain calm and avoid overreacting to isolated incidents.

In the western city of Nantes late Monday, a van burst into a Christmas market, injuring 10 people before the driver began stabbing himself. The night before, in the eastern city of Dijon, a driver shouting 'God is great' in Arabic ran down several crowds, injuring 13 people before coming to a stop.

And on Saturday, an attacker knifed three police before he was shot to death by one of the officers. The man's brother was arrested the same day in Burundi, their homeland. French counterterrorism investigators were called in to the case.

"These three events have no link," French President Francois Hollande said.

The drivers in the attacks in Nantes and Dijon both had long histories of mental illness, officials said.

Prime Minister Manuel Valls said there were no ties with terrorism in the attacks, but nonetheless announced that security would be increased in public spaces during the holidays.

"Just because someone takes an image pervasive in society at a given moment and wants to take part in a kind of violence seen elsewhere, doesn't mean the person is motivated by politics or religion," said Jean-Marie Le Guen, another top official.

In Nantes, bystanders ran toward the attacker as he was stabbing himself, said Mohammed Bader Ghegate, one of the witnesses who ended up at the man's side. Contrary to media reports, Ghegate said the attacker did not say 'God is great' in Arabic.

"I said that to myself: 'Allahu Akbar, help us so there is no bloodshed,'" Ghegate told The Associated Press.

On Tuesday, the Christmas market was shuttered, and vendors milling around wore white armbands in solidarity.

___

Hinnant reported from Paris.