Clark County Sheriff Kevin McMahill said at a news conference that a handgun was found at the feet of the man who has been identified as Matthew Livelsberger.
Officials believe the shot was self-inflicted.
Livelsberger served in the Green Berets, highly trained special forces who work to counter terrorism abroad and train partners, the army said in a statement.
The FBI says it is "conducting law enforcement activity" in Colorado related to the car blast. (AP PHOTO)
He had served in the army since 2006, rising through the ranks with a long career of overseas assignments, deploying twice to Afghanistan and serving in Ukraine, Tajikistan, Georgia and Congo, the US army said.
He was awarded two Bronze Stars, including one with a valour device for courage under fire, a combat infantry badge and an Army Commendation Medal with valour.
Livelsberger was on approved leave when he died, according to the statement.
The FBI said on Thursday in a post on X that it was "conducting law enforcement activity" at a home in Colorado Springs related to Wednesday's explosion but provided no other details.
The explosion of the truck, packed with firework mortars and camp fuel canisters, came hours after 42-year-old Shamsud-Din Bahar Jabbar rammed a truck into a crowd in New Orleans' famed French Quarter early on New Year's Day, killing at least 14 people before being shot to death by police.
Both Livelsberger and Jabbar spent time at the base formerly known as Fort Bragg, a massive army base in North Carolina that is home to multiple army special operations units.
However, one of the officials who spoke to the AP said there is no overlap in their assignments at the base, now called Fort Liberty.
Seven people nearby suffered minor injuries when the Tesla truck exploded.
Video showed a tumble of charred fireworks mortars, canisters and other explosive devices crowded into the back of the pick-up.
Tesla CEO Elon Musk said on X that "we have now confirmed that the explosion was caused by very large fireworks and/or a bomb carried in the bed of the rented Cybertruck and is unrelated to the vehicle itself".
"All vehicle telemetry was positive at the time of the explosion," Musk wrote.
Authorities know who rented the truck with the Turo app in Colorado, sheriff Kevin McMahill of Clark County said on Wednesday.
He did not release the person's ID, however.
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