Las Vegas Gunman Shot Guard Before Firing on Crowd

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Mourners hold their candles in the air during a moment of silence during a vigil to mark one week since the mass shooting at the Route 91 Harvest country music festival, on Oct. 8, 2017 in Las Vegas.

Law enforcement authorities on Monday made a significant change to the timeline of the Las Vegas mass shooting, saying the gunman shot a hotel security guard before he opened fire on concert-goers.

Clark County Sheriff Joe Lombardo had previously said the guard was shot after gunman Stephen Paddock fired at the country music festival and that the guard’s arrival in the hallway of the Mandalay Bay hotel may have caused Paddock to stop firing.

Mandalay Bay hotel-casino security guard Jesus Campos told investigators that he had been responding to a report of an open door when he heard drilling in Paddock’s room.

Lombardo says Paddock shot at Campos and then, minutes later, shot at the crowd below.

It was not immediately clear why the timeline of the shooting changed a week later or what the impact could be on the investigation.