A suspect has shot dead one person and seriously wounded another inside a supermarket in the southern French town of Trebes, a police union official said.

The suspect earlier fired six shots at police officers who were on their way back from jogging near the city of Carcassonne on Friday morning, according to Yves Lefebvre, secretary general of the SGP Police-FO union.

One police officer was injured in the shoulder but is not in a life-threatening condition, Mr Lefebvre said.

Graphic locates Trebes in southern France where a gunman is holding several people hostage
(PA graphic)

The police officers, based in the southern city of Marseille, were on a temporary mission in Carcassonne, he said.

French President Emmanuel Macron has asked interior minister Gerard Collomb to go to the site of the incident.

Anti-terror prosecutors have taken over the investigation.

The move came after unconfirmed media reports that the assailant claimed connections to Islamic State.

Prime minister Edouard Philippe has said all information suggests it “seems to be a terrorist act”.

Special police units have been sent to the scene at a Super U supermarket and local authorities have blocked roads and urged residents to stay away.

France has been on high alert since a string of Islamic extremist attacks in 2015 and 2016 that killed more than 200 people.