It's thought the gunman behind the Las Vegas massacre altered weapons to make them more deadly.

Dozens of weapons were found in Stephen Paddock's hotel room after he fired rounds of bullets into a music festival crowd.

The death toll stands at 59, with hundreds more injured as FBI investigations continue.

US correspondent Richard Arnold told Larry Williams, Paddock bought semi-automatic guns legally, but cranked them up with add-on systems.

He said gadgets that up a gun's capability are available online - thanks to a lapse in US law.

"The gun lobby has the politicians in its pocket. It's harder to shoot accurately using these device but when you're raining down bullets that doesn't seem to matter."

LISTEN ABOVE AS RICHARD ARNOLD SPEAKS WITH LARRY WILLIAMS