Las Vegas: The girlfriend of the Las Vegas gunman says she thought her "kind, caring, quiet" partner was trying to break up with her when he bought her a plane ticket to the Philippines two weeks ago and wired her $US100,000 ($127,000) to buy a house in her home country.

Marilou Danley, 62, arrived in the US from the Philippines on Wednesday night and has been with the FBI for more than 15 hours.

Her boyfriend Stephen Paddock, a retired accountant and multi-millionaire gambler, killed 58 people and injured more than 500 when he fired on a crowd at the Route 91 Harvest country music festival from his 32nd floor room at the Mandalay Bay hotel on Sunday night, local time. He shot himself dead shortly before police stormed into his hotel room.

He had 47 guns, 33 of which were accumulated over the last year, the Federal Bureau of Alcohol, Tobacco and Firearms said.