US officials reacted cautiously meanwhile to an IS claim that Stephen Craig Paddock, 64, had carried out Sunday night's massacre on the Las Vegas Strip on behalf of the jihadist group.
Police said Paddock, a retired accountant with no criminal record, smashed windows in his 32nd floor hotel room shortly after 10:00 pm and trained bursts of automatic weapons fire on thousands of people attending a country music concert below.
Investigators recovered 23 guns, including assault rifles, from Paddock's room at the Mandalay Bay hotel, and another 18 firearms along with bomb-making materials at one of his two homes.
Consular staff from across the US are helping in the search for any Australians caught up in the deadly Las Vegas mass shooting.
No Australians have so far been identified as dead or injured but Australian authorities are working with their Canadian and British counterparts and contacting hospitals.
"We've increased our consular staff in both Los Angeles and Las Vegas. We are sending staff from our Washington embassy, experienced consular staff," Foreign Minister Julie Bishop told ABC radio on Tuesday.
Country music star Jason Aldean rushed off stage when the shooting began, and concert-goers scattered in panic, frantically seeking cover as bullets rained down from above.
"We saw bodies down. We didn't know if they had fallen or had been shot," said Ralph Rodriguez, an IT consultant from the Pomona Valley, near Los Angeles, who was at the concert with a group of friends.
"People started grabbing their loved-ones and just strangers, and trying to help them get out of the way," Rodriguez said.
The Islamic State group claimed that Paddock was one of its "soldiers" but the FBI said it had found no such connection so far and the local sheriff described him as a lone "psychopath."
Police said Paddock killed himself before a SWAT team breached his room in the Mandalay Bay hotel overlooking the venue for the country music concert.
