New Orleans attacker acted alone, vowed loyalty to ISIS, says FBI

New evidence emerges detailing extent of his support for the militant group

A US army veteran motivated by loyalty to ISIS likely acted alone when he killed and injured dozens in a truck attack against a New Orleans crowd of New Year revellers, the Federal Bureau of Investigation (FBI) said on January 2.

Despite initial concerns that Shamsud-Din Jabbar had accomplices still on the run, preliminary investigations show he likely was alone, FBI deputy assistant director Christopher Raia said. "We do not assess at this point that anyone else was involved," he added.

However, new evidence emerged detailing the extent of the US citizen's loyalty to ISIS and his plans to cause mayhem in the attack, which killed 14 and injured more than 30 in the French Quarter district, ending only after he was shot by police.

"He was 100 per cent inspired by ISIS," Mr Raia said.

Just before the attack, in which 42-year-old Jabbar slammed a rented Ford F-150 pickup into the crowd, he "posted several videos to an online platform proclaiming his support for ISIS", Mr Raia said.

A black ISIS flag was affixed to a pole on the back of his vehicle.

In one video, Jabbar explains he originally planned to harm his family and friends, but was concerned the news headlines would not focus on the "war between the believers and the disbelievers".

Mr Raia said Jabbar had planted two homemade bombs in drink coolers in French Quarter streets.