A U.S. law enforcement official, speaking on condition of anonymity, told Reuters authorities to believe 64-year-old Stephen Paddock had at least two such weapons when he fired from his 32nd-floor hotel room, killing at least 59 people and injuring more than 500.
A hotel security guard who approached the room during the rampage was shot through the door and wounded in the leg.
He used at least 10 suitcases to smuggle the weapons into his room after checking in on Thursday last week.
Firing a weapon using a bump stock involves using the power of the recoil when shooting. Several pounds of ammonium nitrate, a fertilizer that can be turned into explosives, were in his auto, authorities said.
Stephen Paddock's only connection to crime before now was his father.
Special agents from San Francisco arrived to assist in the investigation and said that 47 firearms were recovered from three locations: the hotel room and two locations in Nevada - Mesquite and Verdi.
Paddock had checked into his rooms, overlooking the outdoor concert venue, on September 28.
Mr Paddock, who killed himself, also had a stockpile of 23 weapons in the hotel suite.
At least 58 people were killed when Paddock opened fire into a crowd of approximately 22,000 at an outdoor country music festival from the 32nd floor of Las Vegas' Mandalay Bay Resort and Casino on Sunday night, police said. "I absolutely wish that had happened".
"He was a wealthy guy and he liked to play video poker and he liked to go on cruises", the gunman's seemingly baffled brother Eric Paddock told reporters from his doorstep in Orlando, Florida, on Monday.
Paddock is said to have been a retired accountant who had no previous criminal record, known affiliation with a terror group or history of mental illness.
Stephen Paddock's retirement community neighbors have described him as quiet and reclusive.
Stephen Paddock would have been around 6 or 7 years old when he lived in Tucson, though it's not clear for how long.
"Most shooters are fairly young", Dugan said. "He knew how he was going to do it, and it doesn't seem like he had any kind of escape plan at all", Van Zandt said.
A victims' fund has been started on GoFundMe by Steve Sisolak, the Clark County, Nevada, commission chair. "She is so warm, so outgoing", Dixon said. So many people have volunteered to give blood that appointments are set several days ahead. Is the Las Vegas shooting linked to ISIS? "May God bless them with the peace and comfort only He can provide in such tragic and heartbreaking moments". Chief Soto offered condolences to Sheriff Lombardo and his staff and offered to provide LVMPD with any assistance and/or resources RPD may provide.
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