UPDATE: New information has been released about the 12 minutes it took police to respond to the mass shooter's hotel room.
Last week, Sheriff Lombardo said Mandalay Bay security guard Jesus Campos called in a barricaded door at 9:59 p.m. He says Campos was shot shortly after that. Shots were first fired onto the festival crowd at 10:05 p.m., and police arrived at Stephen Paddock's hotel suite at 10:17 p.m.
According to ABC News, there were police officers inside the Mandalay Bay hotel when the shooting started, but they immediately went to secure another event. Since the Mandalay Bay is so large, officers at the festival across the street were actually able to respond even faster.
By the time police arrived, the shooting had stopped.
Sheriff Joe Lombardo released a new timeline of the events surrounding the 1 October shooting in Las Vegas.
Lombardo said that MGM Resorts was correct when they said that Mandalay Bay security guard Jesus Campos was shot 40 seconds before Steven Paddock began firing on the Route 91 Festival crowd.
The sheriff still stood by the 9:59 p.m. time released earlier this week, though said the circumstances associated with that time have changed.
WATCH: Several statements by Sheriff Lombardo from the press conference are in the media player at the top of this page. Includes an update on the injured, fuel tanks that were shot, and autopsy of Paddock.
An entry was made in the Mandalay Bay security log at 9:59 p.m. because that was the time Campos encountered a barricaded door that was near Stephen Paddock's room.
The rest of the timeline remains the same. Paddock began firing into the crowd around 10:05 p.m., he stopped shooting 10 minutes later, and police arrived at his room at 10:17 p.m.
Lombardo also addressed the discrepancy on when Stephon Paddock checked into his room at Mandalay Bay. He said that they now know Paddock arrived on Sept. 25 and changed his registration on Sept. 28 so that the name of his girlfriend, Marilou Danley, was included.
According to Sheriff Lombardo, the timeline was compiled from multiple sources of information including:
Officer Campos' statements
Police officer body camera video
Video from cameras inside the Mandalay Bay
LVMPD dispatch records
Videos from other cameras, individuals around the event
The sheriff also talked about two Las Vegas Metropolitan Police Department officers who were injured during the 1 October shooting.
According to Lombardo, Paddock began firing at police officers once they arrived at the festival site. Officer Brady Cook sustained gunshot wounds to his shoulder, bicep, chest, and back. (Lombardo noted that Cook wasn't shot four times - those injuries include entry and exit wounds.)
In spite of his injuries, Cook asked Lombardo if he could come back to work on Oct. 13.
Lombardo also talked about Officer Samuel Wittwer, who broke his leg while trying to help Route 91 Festival attendees escape from the gunfire. Wittwer remained at the scene in spite of his injury to make sure others were safe.
Correction: An earlier version of this story misspelled Officer Samuel Wittwer's name. We have since corrected the spelling error.