A man who shot dead five people and wounded 11 others at a famed Christmas market in the eastern French city of Strasbourg had pledged allegiance to the Islamic State group in a video, a judicial source said on Saturday.

The video was found in a USB key belonging to Cherif Chekatt, 29, who was shot and killed by police after a two-day manhunt in the city following the December 11 attack.

The Islamic State group claimed Chekatt was one of their “fighters”, but this was dismissed by French Interior Minister Christophe Castaner

The attack on Strasbourg’s cherished Christmas market, a target full of religious symbolism, evoked France’s difficulties in integrating western Europe’s largest Muslim minority and dealing with homegrown militants inspired by Islamic State.

Strasbourg Mayor Roland Ries described the attack as indisputably an act of terrorism, expressed relief that Chekatt had been killed and said everyone in Strasbourg, on eastern France’s Rhine river border with Germany, felt the same.

French troops, who have been used to bolster national security since a wave of Islamic State-inspired attacks began in France in 2015, stood guard at the open-air market when it reopened days later.

“I think it will help to get back to a life that I would describe as normal,” Ries told reporters after the news Chekatt had been killed.

“With the death of this terrorist … citizens, like me, are relieved.”

Islamic State claimed Chekatt as one of its soldiers, saying he “carried out the operation in response to calls for citizens of coalition countries” fighting the militant group.

IS provided no evidence for the claim and Castaner called it “opportunistic”.

“Nothing indicates (Chekatt) was part of a network. There is nothing to suggest he was being protected by such but the investigation is not yet over,” Castaner told Europe 1.

He described Chekatt as a long-time delinquent whose Islamic beliefs were radicalised during previous periods in prison.

Police were still interrogating seven associates on Friday, including his parents, to determine whether he had accomplices.

France ramped up its security threat to its highest level after Chekatt struck late on Tuesday.

Prime Minister Edouard Philippe promised an extra 1800 troops would be put on patrols with a special focus on Christmas markets.

The outdoor market in Strasbourg, centred around a towering Christmas tree in Place Kleber, draws more than two million visitors each year.

Christmas markets have been a feature of the Alsatian city since the early 15th century.

Three people died in the assault in the vicinity of the Christmas market and several were wounded, including one person fighting for their life, Paris Prosecutor Remy Heitz said.