French officials urged calm late Monday after a second attack involving a car hitting pedestrians in as many days injured 10 people in the western town of Nantes. 

Authorities said a driver crashed his van into a crowded Christmas market before stabbing himself several times. He is among five people hospitalized in serious condition. Local prosecutor Brigitte Lamy said the incident was an isolated incident and "not a terrorist act", though police investigations were continuing late Monday.  

Lamy said the driver was a 37-year-old man born in the western French city of Saintes, about 150 miles south of Nantes. Images on French television showed a white Peugeot van in the market at the city's main square, surrounded by police and rescue workers.

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.

The Nantes attack came one day after another driver ran down 13 bystanders in the eastern city of Dijon, and two days after Bertrand Nzohabonayo, a 20-year-old recent convert to Islam, knifed two police officers outside the city of Tours before being killed by police. 

In a signal of how serious the government was taking the attacks, Prime Minister Manuel Valls issued a statement late Monday calling for calm and vigilance.

The series of attacks, he said, "concerns us all."

Interior Minister Bernard Cazeneuve headed to Nantes Monday evening after spending the day in Dijon.

Prosecutor Marie-Christine Tarrare said the driver behind Sunday's attack in that city has a long history of severe mental illness and no links to terrorism. She added that the 40-year-old was taken into custody and has admitted his role in the attack. Tarrare described the man as a French-born son of North African immigrants, acted alone and had no religious motivations, but was upset at the treatment of Chechen children.

He shouted 'God is great' to give himself courage to act, and not out of religious belief, Tarrare said.

Prosecutors said the attacker in Dijon had been hospitalized 157 times.

Also Monday, intelligence services in the African nation of Burundi said police had arrested Nzohabonayo's 19-year-old brother, Brice. Burundi intelligence spokesman Telesphore Bigirimana told the Associated Press that they had been tipped off about the brothers' movements since 2013. He said the two moved between France and Burundi and there were concerns about how radical they had become after converting to Islam.

Burundi has been on alert over possible attacks by Somali militant group al-Shabab over the presence of Burundian troops in the African Union Mission in Somalia.

The Associated Press contributed to this report.