Stephen Paddock: Donald Trump describes Las Vegas shooter as 'very sick, demented man'

'We are looking into him very, very seriously', the President added

President Donald Trump and first lady Melania Trump board Air Force One for a trip to Puerto Rico (AP)

Donald Trump has described Stephen Paddock – who killed 59 people and injured more than 500 in America's deadliest mass killing in modern history – as a “very sick, demented” man.

Multiple government agencies are investigating what led the 64-year-old to open fire from a Las Vegas hotel room into a crowd of some 22,000 concert-goers.

“He’s a sick man, a demented man. A lot of problems, I guess,” Mr Trump told reporters before boarding his Marine One helicopter as he makes his way to hurricane-ravaged Puerto Rico.

“We are looking into him very, very seriously. But we’re dealing with a very, very sick individual,” the President added.

Police said they believed Mr Paddock killed himself before they stormed his hotel room on the 32nd floor of the Mandalay Bay, which is next to the concert site.

The shooting has reignited the controversy over gun ownership laws, but the White House and Republicans have brushed aside attempts to discuss gun policy.

When asked whether the Las Vegas shooting would prompt him to take up gun control legislation, Mr Trump responded: “Look, we have a tragedy. What happened is, in many ways, a miracle.”

“The police department, they’ve done such an incredible job,” he added. “And we’ll be talking about gun laws as time goes on. But I do have to say, how quickly the police department was able to get in was really very much of a miracle. They’ve done an amazing job.”

Police found at least 23 weapons inside Mr Paddock's hotel room, including multiple rifles.

Mr Trump will visit Las Vegas on Wednesday.

Christopher Sullivan, general manager of Guns & Guitars, a gun shop in Mesquite, Nevada, confirmed that Mr Paddock had bought firearms at his store. Mr Paddock never gave any indication that he might have been unstable, Mr Sullivan said in a statement.

The gun shop owner also said Mr Paddock showed no signs of being unfit to buy guns. All the purchases were legal and cleared routine federal screening, Mr Sullivan said.

Paddock lived in a house in a retirement community in the small city of Mesquite, which is about an hour and a half drive from Las Vegas.