Survivors of the supermarket siege said he shouted "Allahu Akbar" and identified himself as a supporter of Islamic State willing to die for Syria.

He lived with his mother and sisters, a neighbour told Reuters, in a charmless social housing block outside Carcassonne's famed walled city, a UNESCO heritage site.

"It was a calm family," a 17-year old girl who lives in the same building told Reuters, declining to give her name.

Although the area was recently renovated, like many of the poor neighbourhoods that ring French cities it still suffers from crime. Local newspapers had recently reported a playground had been set on fire. On Friday, gangs of youths threatened journalists seeking reactions from locals.

Neighbours said Lakdim was a regular visitor to the Carcassonne mosque. Recent mug shots showed him sporting a long black beard.

On Friday morning, after stealing a white Opel Corsa, killing the passenger and injuring its owner, he drove towards a nearby military barracks where he waited a few minutes, the prosecutor said.

Changing target, he headed towards the riot police's garrison, where he shot at four officers jogging outside, before driving away.

Storming into a supermarket in the nearby town of Trebes, he shouted "God is Greatest" and shot dead a customer and an employee before taking the other 50-or-so shoppers hostage.

During his standoff with police, he briefly came out of the supermarket, threatening to "blow everything up", the prosecutor said.

When he started shooting at a gendarme who had swapped himself with a female hostage, anti-terrorism police launched the assault in which he was killed.

Reuters