A motorist ploughed a car into a cafe terrace in Olympic host city Paris on Wednesday evening, killing one person and seriously injuring several others in a suspected accident, officials told AFP.
The incident struck less than 10 days before the opening of the Olympic Games in the French capital on July 26.
The public prosecutor's office said one person had been arrested -- the driver of the vehicle -- despite earlier comments from investigators suggesting a passenger was also detained.
The prosector's office said it was not established whether there had been a passenger.
Earlier, the police source had said three of the injured people were in a critical condition.
Another police source said the initial hypothesis was that the incident, which happened at around 7:30 pm (1730 GMT), was a traffic accident.
The dark-coloured Toyota car stood with its bonnet crumpled at the entrance to the Le Ramus bar in the city's northern 20th district, an AFP reporter saw.
District mayor Eric Pliez told reporters that police had checked there were no explosives in the car.
He said all those injured were customers of the bar.
"We are very upset. This has shaken all of us," added one of his deputies, Vincent Goulin.
There was a large police presence around the terrace of the bar tucked in behind the world-renowned Pere Lachaise cemetery, the final resting place of the likes of Edith Piaf, Oscar Wilde and Jim Morrison.
At least four fire engines were also stationed close by while soldiers patrolled the nearby Gambetta Square.
France is on high alert ahead of the Games, having been the victim of numerous terror attacks in recent years.
The incident comes two days after a soldier was stabbed in the back by a 40-year-old man at a major train station in northern Paris.
The soldier, whose life was not in danger, was part of a special military operation to protect sensitive sites in Paris that was deployed following the 2015 Islamist attacks on the satirical Charlie Hebdo newspaper.
A waiter at another cafe around 200 metres away said he saw the car come past "at top speed" and then heard a loud noise.
The car "went the wrong way down a one-way street and ploughed" into the terrace, added the waiter, who has worked in that street for three years and spoke on condition of anonymity.
He said he approached the crash site and saw people fleeing and a body.
"These are colleagues, they're neighbours, I know them," he told AFP with tears in his eyes.
"It's a calm street, nothing ever happens here."
He said police arrived "very, very quickly" on the scene.
He said he saw two women trying to treat the victims.
During the Olympics there will be 35,000 police officers and 18,000 soldiers providing security for the Games.
From 5:00 am on Thursday until the opening ceremony on July 26, a special anti-terrorism security perimeter will be activated around the river Seine in Paris.
More than 300,000 spectators are expected to watch the opening ceremony along the banks of the Seine -- the first time ever that the Games' curtain raiser will be held outside of a stadium.
Despite a "resurgence" of the terrorist threat throughout France, national anti-terrorist prosecutor Olivier Christen on Tuesday said that the Olympic and Paralympic Games in Paris "are not the subject of specific targeting by international terrorist organisations".
