New Orleans: A US Army veteran with an ISIS flag on his truck swerved around makeshift barriers and plowed into New Orleans' crowded French Quarter on New Year's Day, killing 15 people in an attack officials believe was carried out with the help of others.

The suspect, identified as Shamsud-Din Jabbar, 42, a US citizen from Texas who once served in Afghanistan, was killed in a shootout with police after ramming the crowd.

The attack injured about 30 other people, including two police officers wounded by gunfire from the suspect. It took place around 3:15 am (0915 GMT) near the intersection of Canal and Bourbon Streets, a historic tourist destination known for its music and bars where crowds were celebrating the new year.

Police and political leaders vowed to capture any accomplices. With the perceived danger ongoing, officials postponed the Sugar Bowl, a classic college football game played in New Orleans each year on New Year's Day. The game between Notre Dame and Georgia was put off for 24 hours until Thursday night as police swept parts of the city looking for possible explosive devices and converged on neighbourhoods in search of clues. The city will also host the NFL Super Bowl on February 9.

The FBI said that police found weapons and a potential explosive device in the vehicle and that two potential explosive devices were found in the French Quarter and rendered safe.

An ISIS flag was attached to the trailer hitch of the rented vehicle, prompting an investigation into possible links to terrorist organizations, the Federal Bureau of Investigation said in a statement.

"We do not believe that Jabbar was solely responsible. We are aggressively running down every lead, including those of his known associates," FBI Assistant Special Agent in Charge Alethea Duncan told reporters, adding that investigators were looking into a "range of suspects."

Biden condemns attack

US President Joe Biden condemned what he called a "despicable" act and said investigators were looking into whether there might be a link to a Tesla truck fire outside a Trump hotel in Las Vegas. So far, there was no evidence linking the two events, Biden said.

"The FBI also reported to me that mere hours before the attack, he posted videos on social media indicating that he's inspired by ISIS, expressing the desire to kill," Biden said of the New Orleans suspect.

CNN, citing officials briefed on the investigation, said the suspect recorded videos in which he mentioned dreams about joining ISIS. Officials told CNN the suspect, obscured by darkness in the videos, spoke about his divorce and plans to gather his family for a "celebration" with the intent of killing them. He later changed his plans and said that he joined ISIS, CNN said.

ISIS - often called Islamic State or ISIL - is a Muslim militant group that once imposed a reign of terror over millions of people in Iraq and Syria until it collapsed following a sustained military campaign by a US-led coalition.

Public records showed Jabbar worked in real estate in Houston. In a promotional video posted four years ago, Jabbar described himself as born and reared in Beaumont, a city about 80 miles (130 km) east of Houston, and said he spent 10 years in the US military as a human resources and IT specialist.

Jabbar was in the regular Army from March 2007 until January 2015 and then in the Army Reserve from January 2015 until July 2020, an Army spokesperson said. He deployed to Afghanistan from February 2009 to January 2010 and held the rank of staff sergeant at the end of service.

'Screaming and debris'
Mike and Kimberly Strickland of Mobile, Alabama, said they were in New Orleans for a bluegrass concert and heading back to their hotel just 20 yards (meters) from where the truck hit some pedestrians.

"There were people everywhere," Kimberly Strickland said in an interview. "You just heard this squeal and the rev of the engine and this huge loud impact and then the people screaming and debris - just metal - the sound of crunching metal and bodies."

About 400 officers were on duty in the French Quarter at the time of the incident, including a number who had established a makeshift barrier to prevent anyone from driving into the pedestrian zone, police said.

"This is not just an act of terrorism, this is evil," Police Chief Anne Kirkpatrick told reporters.

In response to vehicle attacks on pedestrian malls around the world, New Orleans was in the process of removing and replacing the steel barriers known as bollards that restrict vehicle traffic in the Bourbon Street area.

Construction was due to be completed in time for the Super Bowl. As a temporary measure, police vehicles and officers attempted to provide a barrier, Kirkpatrick said.

"This particular terrorist drove around, onto the sidewalk and got around the hard target," Kirkpatrick said.

Jon Alterman, Middle East expert at Washington's Center for Strategic and International Studies, said ISIS, though diminished in the field, has long attempted to radicalize people online, with only occasional success.

"It doesn’t take a huge operation to find individuals in personal distress and give them a sense that their life can have some greater meaning," he said in an email.