A driver drove into a Christmas market in western France, injuring at least 10 people before stabbing himself, according to police, a day after a similar attack in another French city.
At least four people were badly hurt, one of whom was critical, after the incident in the city of Nantes on Monday night, the third attack in three days by individuals against civilians or security forces in France, a police statement said.
The latest attack in France's sixth-biggest city happened at about 7pm local time (18:00 GMT) as people across the country crowded shops and markets in search of last-minute Christmas presents.
Video images on French television showed a white Peugeot van in the Christmas market, which was being held in the city's main square.
Authorities were quick to stress there were "no apparent terrorist motives" in the latest attack, describing the perpetrator as "unbalanced".
On Sunday a man shouting "Allahu Akbar", God is Greatest in Arabic, drove into pedestrians on the streets of the eastern city of Dijon, injuring 13. The driver was suffering from a severe psychological disorder, a prosecutor said.
On Saturday a man was shot and killed by police after walking into a police station in the central town of Joue-les-Tours and attacking three officers with a knife. He had also yelled, "Allahu Akbar".
Brigitte Lamy, a local prosecutor, said "we cannot speak of a terrorist act," adding that initial evidence pointed instead to an "isolated case".
Speaking in Nantes, Bernard Cazeneuve, France's interior minister, said the attacker appeared to be "unbalanced" and not motivated by politics or religion.
President Francois Hollande asked the premier to convene an emergency cabinet meeting on Tuesday to discuss the attacks.
Hollande has urged the French public not to panic while Manuel Valls, prime minister, reiterated an appeal for "cool-headedness".