An 83-year-old driver struck a group of cycling children in western France on Wednesday, injuring seven, three of them seriously, officials said.

The group of 12 children, aged 8 to 11, was heading from a leisure centre to a park on bicycles mid-morning when a woman driving a small hatchback hit them at a roundabout in the west coast city of La Rochelle, officials said.

Seven children were hospitalised after the front-impact accident with the car.

A jumble of cycling helmets, a fluorescent yellow vest and tangled bicycles could be seen at the scene, according to an AFP correspondent.

More than 30 firefighters and several ambulances have been dispatched to the site of the accident.

One girl was airlifted to hospital in the city of Tours, local official Emmanuel Cayron told reporters, after initially saying she had been taken to Poitiers.

Two others were labelled an extreme emergency and also rushed to hospital.

Four other children were hospitalised in La Rochelle, Cayron said.

The toll is very heavy, he said. Our priority was to rescue the children, and also to take care of those who were not physically injured but very shocked by this accident. The scene was harrowing for all those who have seen it.

The children were hit on a two-way traffic lane, according to prosecutors, who opened an investigation into unintentional injuries. The immediate reason for the collision was not known.

A local who gave only his first name, Yann, said the woman drove in the opposition direction. She no longer knew what she was doing, he told AFP.

I heard the sound of the impact, I heard the screams, he said. There have been four accidents in five years on this avenue because people drive too fast.

The motorist was Initially placed in police custody for questioning but was later hospitalised.

The driver, aged 83, tested negative for alcohol and narcotics, regional prosecutor Arnaud Laraize said in a statement.

The mayors office said the children, who regularly travelled on bicycles, were accompanied by two activity leaders. (AFP)