Police and officials survey an area in the French Quarter on Orleans Street near the St. Louis Cathedral in New Orleans, La., Jan. 1. UPI-Yonhap

Shamsud-Din Jabbar, 42, a U.S. citizen from Texas identified by police as the suspect in a truck attack that killed several people during New Year's celebrations in New Orleans, La., U.S., is seen in this undated handout photograph obtained by Reuters on Jan. 1.

A U.S. 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 U.S. citizen from Texas who once served in Afghanistan, was killed in a shootout with police after ramming the crowd.

The attack, which injured 30 other people, took place around 3:15 a.m. (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 neighborhoods in search of clues.

The city will also host the NFL Super Bowl on Feb. 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 found on the rented vehicle, prompting an investigation into possible links to terrorist organizations, the Federal Bureau of Investigation said in a statement.

Not solely responsible

"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.

Asked how many potential accomplices the FBI was looking into, she said it was a "range of suspects" and urged anyone who had contact with Jabbar in the previous 72 hours to contact authorities.

CNN and the Associated Press had reported that surveillance video captured three men and a woman placing an improvised explosive device in the French Quarter, but the law enforcement sources they cited later backed off that conclusion, saying it was unclear what the people in the video had done.

The FBI, which is the lead investigator on the case, also said it and the Harris County Sheriff's Office were conducting an operation in a north Houston neighborhood in an area matching one of Jabbar's known residences.

CNN, citing unnamed sources, reported that investigators found writings with the suspect that the FBI believes support the view that the vehicle attack was inspired by ISIS.

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 U.S.-led coalition.

Public records show Jabbar worked in real estate in Houston. In a promotional video posted four years ago, Jabbar describes himself as born and reared in Beaumont, a city about 80 miles (130 km) east of Houston, and saying he spent 10 years in the U.S. 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.

The French Quarter, near Bourbon Street is blocked off late morning with a heavy police and FBI presence after a Terrorist attack early in the morning in New Orleans, La., Jan. 1. AFP-Yonhap

'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 made an impact with 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 of officers 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. She said two police officers were wounded by gunfire and in stable condition.

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 began in November and was due to be completed in time for the Super Bowl, officials said. In the meantime, 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.

While mass shootings are more commonly a threat in the United States, vehicle rammings have been used to kill civilians in the U.S. and around the world.

Last month in Germany, a 50-year-old man was charged with multiple counts of murder and attempted murder after police said he plowed a car through crowds at a Christmas market in Magdeburg, killing five people and injuring scores. (Reuters)