A rally car ploughed into the crowd during a race in southern France on Saturday, killing at least two people and badly injuring about 15, including children, firefighters said.
The orange-coloured car competing in the 14th annual Maures regional rally veered off the road at Plan-de-la-Tour in the Var region near the Mediterranean coast, killing a 20-year-old spectator and a race marshal (50).
Among the injured, four including two youths aged 12 and 17 were critical. A nine-year-old boy was also wounded.
"The toll could worsen," Stanislas Cazelles, an official from the Draguignan commune, told reporters.
He added that the second day of the rally has been cancelled, "given the gravity of the situation."
The public prosecutor in Draguignan, Danielle Drouy-Ayral, said an official from her office was en route to oversee an investigation.
According to initial reports, it appears the driver, whose identity has not been released, made a mistake at an intersection where he was supposed to turn right, but instead drove straight ahead, crashing into the spectators.
"The priority is to find out the causes of this accident. The vehicle will be examined. The driver of the vehicle, who is in shock, has been hospitalised and placed in custody, and the co-driver will be heard," said a prosecutor Julien Ficara.
Investigators have begun collecting photos and footage from spectators, in order to determine the circumstances of the accident.
Visibly shocked by the accident which occurred around 4:30pm (1430 GMT), several competitors at the rally were in tears.
Minister for Youth and Sports Valerie Fourneyron said in a statement that the accident poses "a serious question of public security during automobile events."
"With the interior minister we want to meet the concerned people as soon as possible, in order to take necessary measures quickly," she said.
Several fatal accidents have occurred recently during car rallies in France.
On 28 April, a 65-year-old spectator, who was at a zone that was off limits to the public, was hit by a car during a rally in the south-east of the country.
On 12 November, a 19-year-old was killed during a rally in eastern France.