US President Donald Trump has condemned Las Vegas attacker Stephen Paddock as a “sick” and “demented” man as police continue to search for a motive behind the mass shooting.
Paddock had amassed an arsenal of at least 42 guns, explosives and several thousand rounds of ammo, police said.
But why the multi-millionaire property investor, who liked to gamble, carried out the attack on country music fans attending the Route 91 Harvest Festival on the Las Vegas Strip on Sunday night remains a mystery.
"He was a sick man, a demented man. Lot of problems, I guess, and we're looking into him very, very seriously," President Trump told reporters as he departed the White House to visit Hurricane-ravaged Puerto Rico.
Asked about gun laws, he added: "We'll be talking about gun laws as time goes by."
A day after the massacre, detectives are still grappling to find a motive for the deadliest shooting in modern US history.
Officers recovered 19 firearms, explosives and ammo from Paddock's home in Mesquite, Nevada, hours after discovering 23 guns in his room at the Mandalay Bay Hotel and Casino from which he shot down at the concert.
Police also found several pounds of ammonium nitrate, a chemical used to make explosives, in the 64-year-old's car.
Some of the firearms recovered from his hotel room had scopes, while two were reportedly modified to make them fully automatic.
A number of people who knew Paddock personally said there was nothing to suggest he was planning a massacre.
Chris Michel who owns a gun store not far from where Paddock lived said he noticed nothing unusual:
"Average everyday 'Joe Blow,'" he said. "Nothing stood out."
"He was talking about how he was new to the area, kind of visiting all the firearm stores in the area.
"Found something on our shelves that he really liked and it took him a couple of different trips, I guess you could say, before he ended up purchasing."
SWAT teams found the retired accountant dead in his room on the 32nd floor of the hotel.
Another home owned by Paddock in Reno, Nevada, is also being searched for clues of a motive.
Sheriff Joe Lombardo described him as a "lone wolf", adding: "I can't get into the mind of a psychopath at this point."
Paddock was "not an avid gun guy" and had become a millionaire through property investments, according to his brother, Eric, who lives in Florida.
"I can't even make something up," he said when asked about what may have motivated his sibling. "There's just nothing."
As the investigation gained pace, details started to emerge about the heroism of his victims as hospital staff battled to help the 527 people injured in the atrocity.
Heather Melton, an orthopaedic surgeon at Henry County Medical Centre in Paris, Tennessee, told WZTV in Nashville that her husband Sonny, 29, who was a registered nurse at the same hospital, "saved my life and lost his" as they tried to escape the bullets.
"I want everyone to know what a kind loving man he was, but at this point I can barely breathe," she told USA Today.