Speaking French and Arabic, the man first threatened a group of soldiers at around 8 am (0600 GMT) in Varces-Allieres-et-Risset, near Grenoble, and then tried to run down another group returning to their barracks from a jog, the sources added.

"The soldiers managed to get up onto the pavement without being hit," army spokesman Colonel Benoit Brulon told AFP.

The driver of the small Peugeot 208 hatchback, who was accompanied by a woman, sped off without causing any injuries.

Prosecutors in Grenoble, a town in the foothills of the French Alps, said the incident was not being treated as a terrorist attack for the moment and the motive remained unclear.

One security source initially told AFP that the driver was among two people arrested around lunchtime in Grenoble, but others later contradicted this as the investigation continued.

The incident comes with France on edge after a jihadist rampage in the towns of Carcassonne and Trebes last week where a 25-year-old gunman killed four people, including a policeman who took the place of a hostage in a supermarket siege.

The people of Trebes paid an emotional farewell to three local victims at a ceremony in the square of the sleepy town on Thursday, held a day after a national tribute to officer Arnaud Beltrame in Paris led by President Emmanuel Macron.

"You fell under the bullets of terrorism and took with you the insouciance of a little town in Occitanie where no one expected to ever experience such happenings," Trebes Mayor Eric Menassi told mourners at the gathering attended by Prime Minister Edouard Philippe.

- Security forces under fire -

Security forces have been repeatedly targeted during the string of jihadist attacks that have claimed the lives of over 240 people around France in the past three years.

At least six security force members have been killed during that period.

In last week's attack, Moroccan-born Radouane Lakdim fired at a group of policemen returning from a jog before storming the Super U store and shooting dead two people. He also killed the passenger of a car he hijacked in Carcassonne.

Beltrame intervened during the supermarket siege to take the place of a cashier Lakdim was using as a human shield.

But after three hours of negotiations the gunman, who claimed allegiance to the Islamic State group, slit Beltrame's throat before himself being shot dead by police.

Paying tribute to Beltrame at a national ceremony in Paris on Wednesday, President Emmanuel Macron said his act of self-sacrifice would "remain etched in French hearts".

Lakdim, who had a criminal record for weapons and drugs offences, was on a watchlist of suspected radicals, but authorities had concluded that he did not pose a threat.

His 18-year-old girlfriend, a radicalised Muslim convert, has been charged with being part of a terrorist conspiracy.

Other deadly assaults on police include the massacre at the Charlie Hebdo satirical magazine in Paris in January 2015, in which two officers were killed, and the fatal April 2017 shooting of a policeman on the Champs Elysees.

The army and police have also been targeted in several non-deadly attacks.

In August 2017, a man ploughed his car into a group of soldiers on anti-terror patrol in the western Paris suburb of Levallois-Perret, injuring six people.

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