US authorities have revealed a security guard was shot dozens of times just prior to the attack on a country music festival in Las Vegas.
Clark County Sheriff Joe Lombardo in Nevada said Jesus Campos had been investigating reports of an open door when he heard noises coming from the room gunman Stephen Paddock was in.
When he investigated, the 64-year-old - who had set up cameras to monitor the hallway outside his room - opened fire through the door, injuring him.
He is reported to have fired a total of 200 shots at the guard, who managed to alert others.
Six minutes after this incident, Paddock opened fire on revelers at the festival on the Strip, killing at least 58 people and injuring more than 500.
Originally, it was believed the guard had been injured after the shooting, before the 64-year-old was found dead in his Mandalay Bay Hotel room.
The incident in Las Vegas has become the deadliest mass shooting in modern history of the United States.