Security posts known as bollards were not in place before a suspect drove a truck into a crowd in the French Quarter of New Orleans early on New Year’s Day, killing 14 and injuring at least 35.
Louisiana officials have said the street barriers were malfunctioning and were undergoing renovations before the city hosts the NFL Super Bowl on 9 February.
The short and sturdy posts – made of concrete, metal or other materials – are meant to block cars from entering pedestrian areas.
Christopher Raia, a deputy assistant director with the FBI, on Thursday called the attack an act of terrorism.
During the early morning hours on New Year’s Day, a police vehicle was parked at an intersection to block access to Bourbon Street in the French Quarter, where the attack took place, but the suspect drove around the car and onto the sidewalk, police said.
Police have named Shamsud-Din Jabbar, a 42-year-old Texas resident and US Army veteran, as the suspect. He died in the attack.
New Orleans Police Chief Anne Kirkpatrick said on Wednesday that police had been “aware of the bollard situation” and took steps to “harden those target areas”.
“We did indeed have a plan, but the terrorist defeated it,” she said.
Ms Kirkpatrick said the city planned to take a number of steps to increase security at the Sugar Bowl American football game, which was moved from Wednesday to Thursday afternoon because of the attack.
Bourbon Street will be re-opened on Thursday shortly ahead of the game.
“We have re-enforced the area,” Louisiana Governor Jeff Landry said on Thursday.
Follow live updates on the attack hereNew Orleans began placing bollards on Bourbon Street over ten years ago, Mayor LaToya Cantrell said on Wednesday.
But, she added, the bollards began to malfunction because of clogs from Mardi Gras beads, leading officials to try to replace them before the Super Bowl, which is scheduled to take place at the Caesars Superdome, near the site of the attack.
At the news conference, Ms Kirkpatrick defended the other security measures the city had in place.
“We did have a car there, we had barriers there, we had officers there, and they still got around,” she said.
A number of cities in the US and around the world have installed bollards to prevent attacks.
New York City put the security measures in place along the Hudson River Park bike path after a man drove a rented pick-up truck into cyclists and runners along the path, killing eight people, in 2017.
It’s too difficult to say for certain whether the New Orleans bollards being in place would have prevented such an incident, said University of Michigan professor and counterterrorism expert Javed Ali.
“He had a Ford 150 pick-up truck. You gun that thing at 50, 60 miles an hour, and who knows, even with bollards in place, would the car just – through physics – have rammed through them anyways?” he said.
“There must have been a lot of luck involved,” Mr Ali added. “That’s unfortunately what happens in these types of attacks.”
A 2017 report commissioned by the city of New Orleans found the French Quarter was a “risk and target area for terrorism that the FBI has identified as a concern that the city must address”.
The report noted that the neighbourhood was “often densely packed with pedestrians and represents an area where a mass casualty incident could occur”.
