Authorities announced on Thursday they are still investigating why a suspect detonated a Tesla Cybertruck outside the Trump International Hotel in Las Vegas a day earlier.

"The motivation at this point is unknown," said FBI Special Agent Spencer Evans, as quoted by AFP. He noted it was "not lost" on investigators that the explosion occurred outside a hotel associated with US President-elect Donald Trump, with a Tesla vehicle which is owned by Elon Musk, a prominent Trump supporter.

"But we don't have information at this point that definitively tells us" it was motivated by any specific ideology, Evans added.

A law enforcement official said on Wednesday, hours after the explosion and fire, that the Vegas incident was being investigated as a possible act of terrorism.

Earlier on Thursday, authorities revealed the suspect in the detonation had suffered a gunshot wound to the head.

"We also discovered through the coroner's office that the individual had sustained a gunshot wound to the head prior to the detonation of the vehicle," said Las Vegas Sheriff Kevin McMahill, suggesting the possibility of suicide before the explosion.

Separately, the FBI stated that there appears to be no connection between the truck explosion in Las Vegas and a deadly truck-ramming incident in New Orleans.

"At this point, there is no definitive link between the attack here in New Orleans and the one in Las Vegas," said FBI Deputy Assistant Director Christopher Raia during a press conference.