FILE - In this Monday, Oct. 9, 2017 file photo, Clark County Sheriff Joe Lombardo discusses the Route 91 Harvest festival mass shooting at the Las Vegas Metropolitan Police Department headquarters in Las Vegas. On Monday, Lombardo said Paddock shot and wounded the security guard outside his door and opened fire through his door around 9:59 p.m. - six minutes before shooting into the crowd. That was a different account from the one police gave last week: that Paddock shot the guard, Jesus Campos, after unleashing his barrage of fire on the crowd. (Erik Verduzco/Las Vegas Review-Journal via AP, File)
FILE - In this Monday, Oct. 9, 2017 file photo, Clark County Sheriff Joe Lombardo discusses the Route 91 Harvest festival mass shooting at the Las Vegas Metropolitan Police Department headquarters in Las Vegas. On Monday, Lombardo said Paddock shot and wounded the security guard outside his door and opened fire through his door around 9:59 p.m. - six minutes before shooting into the crowd. That was a different account from the one police gave last week: that Paddock shot the guard, Jesus Campos, after unleashing his barrage of fire on the crowd. (Erik Verduzco/Las Vegas Review-Journal via AP, File) Credit: Erik Verduzco

The gunman who sprayed more than 1,000 rounds of bullets into a Las Vegas country music concert also took shots at jet fuel tanks and targeted police officers responding to the scene, investigators said Friday in portraying a killer who seemed determined to inflict even more carnage than the 58 people he murdered.

Investigators gave more details on the chronology of events surrounding the shooting and pushed back against criticism that they were changing their story. Shifting accounts about when Stephen Paddock fired his first shots in his 32nd floor Mandalay Bay suite have led to questions about whether police could have done more to stop him on Oct. 1.

“In the public space, the word ‘incompetent’ has been brought forward,” Clark County Sheriff Joe Lombardo said. “I am absolutely offended with that characterization.”

In a chronology provided Monday, Lombardo had said Paddock started spraying 200 rounds from his suite into the hallway of the Mandalay Bay at 9:59 p.m., wounding an unarmed security guard in the leg. He said Friday that the security guard came to a barricaded stairwell door at 9:59 and wasn’t shot until around 10:05 p.m.

About that time, the gunman unleashed a barrage of bullets on the festival crowd. Then he killed himself with a gunshot to the head.

The timeline comes as investigators say they have yet to identify a motive behind the worst mass shooting in modern U.S. history. The FBI says agents have conducted hundreds of interviews, chased nearly 2,000 leads, looked at Paddock’s computers and phone, collected 1,000 pieces of evidence, and analyzed hours of video footage.

“We are establishing a timeline of this suspect’s life, his motivation and everybody associated with him throughout time,” Lombardo said.

The sheriff became emotional describing gunshot wounds one on-duty officer, Brady Cook, received to the shoulder, bicep, chest and back as he arrived in a police patrol car moments after shooting started.

“It is readily apparent to me that (Paddock) adjusted his fire and directed it toward the police vehicles,” Lombardo said. “No matter what his personal vendetta is against the police or not, maybe he was preventing the wolf from getting to his door sooner than later, but he chose to fire upon police vehicles.”

A visual inspection of Paddock’s brain during a coroner’s autopsy found “no abnormalities,” Lombardo said.