Law enforcement agencies are expanding their investigation into the New Year’s ramming attack on New Orleans‘ Bourbon Street which killed at least 15 people and injured dozens more in the early hours of Wednesday.

City and federal officials said an Army veteran — identified as Shamsud-Din Jabbar, 42 — was “hell-bent” on killing as many people as possible. The suspect drove a pickup truck around a parked police car serving as a barricade and plowed into crowds of revelers, officials said.

The suspect mowed down dozens of people over a three-block stretch on the world-famous thoroughfare while firing into the crowd, police said.

The alleged attacker then exited the damaged vehicle armed with an assault rifle and opened fire on police officers, law enforcement officials said. Jabbar was also armed with a handgun, sources told ABC News.

Officers returned fire, killing Jabbar, a U.S.-born citizen from Texas, sources said. At least two police officers were injured, one by gunfire and the other when the officer was pinned by the truck, authorities said.

Althea Duncan, assistant special agent in charge of FBI New Orleans field office, said investigators do not believe Jabbar acted alone.

“We do not believe that Jabbar was solely responsible,” Duncan said during a news conference Wednesday afternoon. “We are aggressively running down every lead, including those of his known associates. That’s why we need the public’s help. We are asking if anybody had any interaction with Shamsud-Din Jabbar in the last 72 hours that you contact us.”

Duncan also said improvised explosives devices and other weapons were found inside the pickup truck used in the attack. She said two additional IEDs were discovered in the French Quarter and rendered safe.

The IEDs found in and around the scene on Bourbon Street were apparently determined to be viable, and investigators were looking for more in the city’s French Quarter, multiple law enforcement sources told ABC News.

The FBI said two devices were found and rendered safe. Crude pipe bombs stuffed with coils and nails were found at the scene along with a grenade, sources said.

New Orleans police have reviewed surveillance video that appears to show several people planting potential explosive devices in advance of the vehicle attack, which led them to believe the suspect did not act alone, sources said. Investigators said they were urgently working to identify the individuals who were seen on camera and to take them into custody.

The FBI offices in New Orleans and Houston released statements late Wednesday announcing searches related to the attack.

“FBI special agents and our law enforcement partners are currently conducting a number of court authorized search warrants in New Orleans and other states,” the FBI’s New Orleans field office said in a statement, adding that they planned to hand over the New Orleans crime scene to local authorities by Thursday morning.

Meanwhile the FBI in Houston posted on X that they and the Harris County Sheriff’s Office were “continuing a court-authorized search of a location near the intersection of Hugh Road and Crescent Peak Drive.”

“At this time, no arrests have been made, and FBI personnel will be at the scene for several more hours,” the post continued.

Authorities are also working to determine whether there may be a link between the New Orleans attack and a Tesla Cybertruck explosion on Wednesday outside the Trump Las Vegas hotel in Nevada, which is being investigated as a possible act of terror, an official said.

The Cybertruck that exploded was rented via the Turo app, as was the truck used in the New Orleans attack, sources told ABC News.

On Wednesday afternoon, the FBI in Houston and the Harris County, Texas, Sheriff’s Office, posted a message on social media that they are “currently conducting law enforcement activity near the intersection of Hugh Road and Crescent Peak Drive in north Houston” related to the New Orleans attack.

“We have secured a perimeter in that area and are asking people to avoid the area,” the notice said. “FBI Houston personnel and specialized teams will be on-site for several hours. This activity is related to this morning’s New Orleans attack, but due to the ongoing nature of the investigation, no further information can be provided.

President Joe Biden, meanwhile, decried what he called a “heinous act” when addressing the New Orleans attack Wednesday night at the Camp David presidential retreat in Maryland.

Biden said that the FBI told him that “mere hours before the attack, [Jabbar] posted videos on social media indicating that he’s inspired by ISIS, expressing a desire to kill.”

Biden also said “law enforcement and the intelligence community” were investigating whether there was “any possible connection” between the New Orleans attack and the Tesla Cybertruck explosion in Las Vegas.

“Thus far, there’s nothing to report on that score,” Biden said.

Biden said that the New Orleans suspect was “an American citizen, born in Texas. He served in the United States Army on active duty for many years. He also served in the Army Reserve, until a few years ago.”

The FBI is studying the videos Biden referenced in his remarks, which the suspect appears to have recorded while driving from Texas to Louisiana, law enforcement sources confirmed to ABC News.

The videos are dark so the suspect isn’t seen but he can be heard talking about his divorce and a desire to kill members of his family before ultimately deciding to carry out the attack on Bourbon Street, according to the law enforcement sources.

The suspect is also heard talking about ISIS, the sources said.

New Orleans Coroner Dr. Dwight McKenna released a statement late Wednesday afternoon that said, “As of now, 15 people are deceased.”

“It will take several days to perform all autopsies. Once we complete the autopsies and talk with the next of kin, we will release the identifications of the victims,” McKenna’s statement continued.

Rep. Troy Carter, D-Louisiana, told ABC News earlier Wednesday afternoon that the number of people killed in the incident had risen from 10 to 15. He said another 25 people were hospitalized with injuries.

This is a developing story. Please check back for updates.