Las Vegas shooter purposely fired at fuel tanks, no connection to extremism: Officials The shooter's brain is being tested for abnormalities, the sheriff said.

 -- Here's the latest on the investigation into the Las Vegas shooting:

— It’s believed gunman Stephen Paddock purposely fired at nearby fuel tanks, Clark County Sheriff Joe Lombardo said.

— The shooter’s brain is being tested for abnormalities, the sheriff said.

— Security officer Jesus Campos first encountered a barricaded door at 9:59 p.m.; was shot later, according to the sheriff.

— The “firing had ceased” by the time police arrived, Lombardo said.

— “No signs of ideology or affiliation to any groups,” FBI Special Agent in Charge Aaron Rouse said.

— Over 1,000 pieces of evidence collected and are being reviewed, Rouse said.

Las Vegas gunman Stephen Paddock is believed to have purposely fired at aviation fuel tanks at the McCarran International Airport near the concert venue where he killed 58 people and injured hundreds more on Oct. 1, authorities said at a press conference today.

"It is believed the fuel tanks were fired upon with intent," said Clark County Sheriff Joe Lombardo.

Lombardo said that he has been advised that there is a "very low probability" that the aviation fuel could be affected by the gunfire.

Paddock shot himself after opening fire on the concert below. A motive for the shooting is still unknown.

Lombardo attempted to clear up some discrepancies, saying that he has been offended by accusations of incompetence on the investigators' parts based on the evolution of the changing timeline of events.

Police told ABC News Friday that they now agree with the statement released by MGM Resorts International on the time in which Mandalay Bay security officer Jesus Campos was shot in the leg. Police previously stated that Campos was shot in the leg at 9:59 p.m., six minutes before the rampage began. They now believe Campos was shot closer to 10:05 p.m., when Paddock first unleashed gunfire on the crowd below.

Authorities now believe that at 9:59 p.m., Campos reported that he had encountered a barricaded door near the suspect's room. Campos was then shot later as he went into the hall.

Lombardo also said that investigators were aware of a discrepancy on the date Paddock checked into the hotel. Paddock had first occupied the room on Sept. 25, but the name and comp status on the room changed on Sept. 28 to include his girlfriend, Marilou Danley, who was overseas at the time of the shooting.

The information for the timeline has been obtained via security logs, officer body logs, body-worn cameras, police department dispatch, hotel and private cameras and interviews, Lombardo said.

The autopsy on Las Vegas gunman Paddock's body did not immediately reveal any abnormalities, though his brain has been taken to a facility for a "microscopic evaluation," Lombardo said.

As of Friday morning, the count on the number of victims injured was at 546, Lombardo said, reminding the public that he had previously warned that information "would change" as the investigation continued.

A total of 45 patients remain hospitalized, some in critical condition. The death toll remained at 58 Friday, but "may raise," Lombardo said.

Seventeen separate medical facilities attended to the hundreds of victims in the aftermath of the shooting, Lombardo said.

"That speaks volumes of the medical community," Lombardo said.

Lombardo also said that he believes Paddock targeted authorities as they arrived on the scene.

"As the officers began to arrive via vehicles, it is readily apparent to me that he adjusted his fire and directed toward the police vehicles," Lombardo said.

Lombardo broke down in tears as he praised members of his department for their response to the shooting.

One of Lombardo's deputies who sustained four gunshot wounds asked him today if he could return to work, the sheriff said.

Lombardo did not take any questions at the press conference, ending it by thanking the Las Vegas community instead.

"I want to thank you for letting me be your sheriff, and Vegas strong," he said.