People tend to the wounded outside the festival ground after a mass shooting in Las Vegas, Nevada

At least 59 people were killed and 527 injured when a gunman rained bullets on crowds at a Las Vegas music festival.

A day on from the deadliest mass shooting in modern US history, police are desperately seeking to understand what drove Stephen Paddock to discharge "clip after clip" into the 22,000 revellers at the Route 91 Harvest festival.

The 64-year-old "lone wolf" attacker, equipped with at least 23 weapons and two tripods, fired rifles out of two different windows from his hotel room on the 32nd floor of the Mandalay Bay hotel before killing himself as police stormed his hideout.

Another 19 guns were found at a property occupied by Paddock about 80 miles away in Mesquite, Nevada.

Officials said he had altered those legally purchased weapons to operate on automatic before he began his deadly spree at around 10:08pm on Sunday.

Las Vegas Sheriff Joseph Lombardo said he was unable to speculate as to his motive, saying: "I can't get into the mind of a psychopath."

Authorities believe Paddock acted alone and dismissed suggestions he had any links to international terror, despite claims from Isis's news agency Amaq that he converted to Islam months before the shooting.

Video posted on social media appeared to show the moment the gunfire broke out as country star Jason Aldean performed, sparking mass chaos and scattering the crowd.

The massacre has reignited an outpouring of anger over the nation's lax gun ownership laws, which are protected by the second amendment.

As the nation was left reeling from the massacre, carried out in one of the world’s most iconic cities, Donald Trump sought to offer solace and condolence, first on Twitter and later in a sombre, televised address.

“In moments of tragedy and horror, America comes together as one. And it always has,” he said

Speaking on Tuesday morning, the President described the killer as a "sick, demented man".

In February, Mr Trump signed a resolution blocking an Obama-era rule that would have prevented an estimated 75,000 people with mental disorders from buying guns.