The suspect in the New Orleans truck attack has been identified as Shamsud-Din Jabbar.
The FBI said he was a 42-year-old US citizen from Texas.
At least 10 people were killed in the suspected terror attack which also injured dozens of others.
Latest updates on New Orleans attack
What do we know about Jabbar?
Army veteran Jabbar is believed to have driven a Ford pick-up truck into a crowd of revellers celebrating the New Year on Bourbon Street in the French Quarter of the southern US city.
Police said he was “hell-bent on creating the carnage and the damage that he did”.
“It was very intentional behaviour. This man was trying to run over as many people as he could,” said police chief Anne Kirkpatrick.
Jabbar died in firefight
Jabbar was killed in a firefight with police following the attack around 3.15am local time (9.15am UK time) on Wednesday.
The bureau said he was driving a Ford pick-up truck, which appeared to have been rented.
It also said an ISIS flag, weapons, and a potential improvised explosive device (IED) were found in the vehicle.
Investigators recovered a handgun and an AR-style rifle after the shootout, a law enforcement official said.
Read more:
What we know so far about atrocity
Eyewitnesses describe carnage of attack
Jabbar was army veteran
He is believed to have been an army veteran and is thought to have been honourably discharged.
He is known to have appeared in a YouTube video talking about his job.
The FBI said it does not believe he was “solely responsible” for Wednesday’s attack, as it asked the public for their help in tracking down his associates.
It is investigating the attacker to determine “potential associations and affiliations with terrorist organisations”.
Police chief Ms Kirkpatrick said the driver, who swerved around barricades, shot and wounded two police officers from the vehicle after it crashed.
The officers were in stable condition, she added.
Previous arrests
Jabbar was arrested in Texas in 2002 for theft, classed as a misdemeanour, and he was fined $100 by a court.
He was also arrested in the same state in 2005 for driving with an invalid licence, also classed as a misdemeanour, and was fined $100 by a court.
What do we know about vehicle used in New Orleans attack?
The FBI said an ISIS flag was found in the truck, along with weapons and a potential improvised explosive device (IED).
Other potential IEDs were also located in the French Quarter, it added.
The historic area is known for attracting large crowds with its music and bars.
