Paris attack: Man shot and arrested on motorway is chief suspect

A man has been shot and arrested by elite police officers after a dramatic car chase on a motorway in northern France suspected of having rammed his car into soldiers in a western Paris suburb, injuring six of them.

The driver slammed his BMW into the group of soldiers who were starting their patrol in what appeared to be a carefully timed ambush before speeding away and sparking a huge manhunt.

His motive was unclear, but officials said he deliberately aimed at the soldiers, and counterterrorism authorities opened an investigation.

In an attack that authorities said bore the stamp of terrorism, the driver appeared to have lain in wait for the soldiers in a pedestrian zone near their base in Levallois-Perret.

The affluent suburb on the northwestern edge of Paris is home to France's domestic counter-terrorism agency.

Several dozen troops from Operation Sentinel, launched in the wake of Islamist attacks in Paris in early 2015, are based there.

The car accelerated into the troops, who were starting their patrol, when they were a few metres away, Interior Minister Gerard Collomb told reporters outside the hospital where the three more seriously injured victims were being treated.

"This was a deliberate act, not an accident," Mr Collomb said, adding that counter-terrorism investigators had taken up the case.

French counter-terrorism prosecutors have opened an investigation into the attack, meaning authorities believe the attack was deliberate and planned with a terrorist motive.

Prime Minister Edouard Philippe also confirmed police had arrested the main suspect behind the attack.

"A suspect who was driving the car involved in the attack has been arrested on the highway between Paris and Boulogne-sur-Mer," Mr Philippe told lawmakers during parliament question time.

French police authorities said in a tweet that 300 officers had been mobilised to track down the suspect, who was stopped a few hours later on the A16 motorway.

A judicial source said the suspect was an Algerian national who was in France legally and French newspaper Le Parisien named him as 37-year-old Hamou B. He is now in hospital after allegedly having been shot five times, French media reports.

One policeman was wounded by a stray bullet in the operation.

French police raided several properties associated with the suspect in the suburban city of Sartrouville about 12 kilometres away from the Levallois, close to where the attack took place.

Police presence was also important in Bezon this afternoon, a bit further north, which is also believed to be linked to the case.

Heavily armed police in masks could be seen entering and leaving a building in Sartrouville.

The attack was the 15th on soldiers and police since they were deployed in large numbers nationwide after a series of Islamist militant attacks over the past two-and-a-half years.

Armed Forces minister Florence Parly said the attack was proof there remained an active threat and that the 7,000-strong Sentinel force was "more necessary than ever".

Patrick Balkany, the mayor of Levallois-Perret, called the attack a "disgusting" act of aggression that was "without any doubt" premeditated.

More than 230 people have died in France in a terror attack since January 2015.

Operation Sentinel has put heavily armed combat troops in public view as they patrol key sites as an annual cost running into hundreds of millions of euros.

Additional reporting by agencies.