An Australian man believes the gunman responsible for a mass shooting in Las Vegas was staying in the room next door to him at the Mandalay Bay Resort and Casino.

New South Wales man and concert producer Brian Hodge, 36, said he ran for his life as hundreds of bullets sprayed into a music festival crowd from a balcony at the hotel as he walked back to his room from a dinner out with his staff.

The gunman who killed at least 50 people and injured hundreds was on the 32nd floor of the Mandalay Bay Resort and Casino, according to Las Vegas police.

Hundreds of fans at the Route 91 country music festival huddled for cover or ran for their lives as the gunfire continued.