FBI agents began interviewing the girlfriend of Las Vegas massacre gunman Stephen Paddock as Donald Trump arrived in the city and said the killer must have had his "wires screwed up".

Mr Trump, who made a private visit to a hospital with his wife Melania, said investigators were "learning a lot more" about Paddock and details would be given at "an appropriate time." He added: "It's a very, very sad day for me, personally."

The president's motorcade passed close to the Mandalay Bay Hotel where Paddock, 64, fired from the 32nd floor, killing 59 people and injuring more than 500 at a country music festival on Sunday night.

As mystery continued to surround his motive Paddock's girlfriend Marilou Danley, 62, a "person of interest" in the case, arrived at Los Angeles airport on a flight from the Philippines.

She was pushed through the airport in a wheelchair by FBI agents who took her to their field office for questioning.

Ms Danley was not arrested but agents were said to have a "lot of questions" and she was being represented by a lawyer.