The decorated special forces soldier who blew up a Tesla Cybertruck outside the Trump International Hotel in Las Vegas shot himself in the head before the blast, authorities said Thursday, adding that his motivation was still "unknown."

Authorities said the suspect — identified as Matthew Alan Livelsberger —was a member of the elite Green Beret forces who appeared to have committed suicide in a Cybertruck filled with fuel containers and fireworks, which then erupted into flames. 

He had a gunshot wound to the head and a gun was found at his feet, officials told reporters at a press conference in Las Vegas. 

"The motivation at this point is unknown," FBI Special Agent Spencer Evans said, as investigators probed the incident as a potential act of "terror."

Video footage outside the Trump International Hotel shows the stainless steel truck parked at the building's glass entrance early Wednesday, then bursting into flames, followed by smaller explosions that appeared similar to fireworks.

Seven people were wounded in the blast. 

The Trump-branded building, which opened in 2008, is part-owned by the Republican president-elect's family business.

Evans said the link to the president-elect was "not lost" on agents, nor was the fact that Tesla is owned by world's richest man — and prominent Trump backer — Elon Musk. 

"But we don't have information at this point that definitively tells us" it was driven by any particular ideology, he said.

Officials said the body had been burned beyond recognition, but that they have a "lot of confidence" it was Livelsberger — identified through his military ID, passport and credit cards.

Guns found

Livelsberger rented the vehicle in Colorado on 28 December, from where authorities tracked him driving it alone through Arizona and New Mexico to Las Vegas, which he reached on 1 January, Las Vegas Sheriff Kevin McMahill said. 

McMahill said Livelsberger was a Green Beret who had spent time in Germany and had been deployed to Afghanistan in 2009.

An army spokesperson said that Livelsberger was "on approved leave at the time of his death," and that he had been awarded multiple Bronze Star Medals, including one for valor.

Investigators said it was not yet clear how the blast detonated, but that the components were mainly consumer products like fireworks and fuel.

But they also said some of the components had not exploded, and that the level of sophistication in the blast was not what they would expect from someone with Livelsberger's military background. 

"I just don't think it was done as well as he was expecting it to be done," McMahill said.

Authorities also confirmed that Livelsberger had purchased two semi-automatic handguns, both of which were found in the Tesla, one at his feet.

'Isolated' incident

The blast came just hours after an electric pickup truck plowed into a crowd in New Orleans' French Quarter, killing at least 14 and injuring dozens.

Initially investigators were probing any potential link between the two incidents, but authorities in New Orleans said Thursday they believe the attacker there acted alone, while the FBI described the Vegas incident as "isolated."

McMahill said Wednesday the fact that it was a Cybertruck "really limited the damage... because it had most of the blast go up through the truck and out," noting that the glass doors of the hotel, just a few feet away, "were not even broken by that blast."

The truck had been rented in Colorado through the carsharing company Turo, police said — the same app that was used to rent the vehicle in the New Orleans attack.

McMahill said Wednesday that was a "coincidence... that we have to continue to look in to."