NEW ORLEANS — Members of Louisiana's congressional delegation declared Wednesday that law officers would track down anyone who helped stage an overnight attack targeting New Year's Eve revelers on Bourbon Street.

"For those who may have played a role in this act of cowardice, we will find you and bring you to justice," Rep. Troy Carter, D-New Orleans, said after a suspected terrorist attack on the city.

According to police, Shamsud-Din Jabbar, 42, of Texas drove a rented pickup truck past a police car blocking Bourbon Street at its intersection with Canal Street and sped into the French Quarter, eventually killing 10 people. ABC News and other media have put the death toll at 15. Police killed the attacker but said he did not work alone.

U.S. Sen. Bill Cassidy, R-Baton Rouge, said the act was clearly terrorism, though investigators have not made that conclusion officially.

"He's clearly trying to commit terrorism, which is not just to kill people, but to commit terror," Cassidy said in an interview with WBRZ. "When you commit terror, you don't go to a small town to kill somebody, you go to the biggest city you can find."

Investigators do not believe Jabbar acted alone. The Associated Press reported Wednesday that investigators had seen video showing three men and a woman placing an improvised explosive device believed to be part of the car attack. AP cited a Louisiana State Police bulletin the news agency had obtained. 

Cassidy was confident that the additional perpetrators would be found.

"This is an act of terrorism and we as the American people will go after them. It appears there is more than one," Cassidy said. "We'll go after them, find them, prosecute them, and throw them in jail. We'll do whatever we can to hunt them down."

U.S. Sen. John Kennedy, R-Madisonville, said the attack was evil.

“For those people who don't believe in objective evil, all you have to do is look at what happened in our city early this morning," he said at a New Orleans news conference. "If this doesn't trigger the gag reflex of every American, ... I'd be very surprised."