He turned the gun on himself before officers were able to break into his room, number 135, in the gold glass skyscraper.
The chemical ammonium nitrate is a high-nitrogen fertilizer that is easily purchased and can be used in homemade bombs.
Another clue that Paddock may have used a souped-up semi-automatic rather than an automatic weapon is the fact that Guns & Guitars, Inc, a weapons shop in Mesquite, Las Vegas, where the shooter bought most of the weaponry used in the shooting, does not sell automatic guns, the Independent reported.
"He went on cruises and gambled".
"We are making progress but I don't have complete answers yet", he said.
Bump stocks have been around for less than a decade, and the US Government gave its seal of approval to selling them in 2010.
He also said their father was a bank robber who was once on the most wanted list.
Law enforcement officials are still working to determine a motive for the shooter but evidence suggests it was a highly planned event, they said at a news conference Tuesday.
The FBI discounted the possibility of worldwide terrorism early on, even after the Islamic State claimed responsibility for the attack.
- The shooting began shortly after 10 p.m. local time (0500 UTC), interrupting a performance by country singer Jason Aldean, who was performing before a crowd of around 22,000 people.
The House was set to vote on the SHARE Act in June, but it was postponed after a gunman opened fire at a congressional baseball game, wounding House Majority Whip Steve Scalise and three others. But, he said, "we'll be back".
Concertgoers fled into casinos and crammed into cars to get away from the shooting.
Trump's trip to Las Vegas follows his Tuesday travel to hurricane-ravaged Puerto Rico.
Hospital emergency rooms were jammed with the wounded.
"They're shooting right at us guys, everybody stay down", one officer said amid the sound of sirens, gunfire and screams.
"We see muzzle flash from the Mandalay Bay", another officer said.
He also declined to call the attack domestic terrorism. "And it always has".
Las Vegas authorities have complained that no members of the public have come forward to help shed light on the motives behind Stephen Paddock's killing of 58 people in the worst mass shooting in US history on Sunday.