The heavily armed officers sweep the Mandalay Bay Resort and Casino on their way up to the gunman’s suite on the 32nd floor, telling patrons to leave and head south away from the shooting.

They climb the building’s stairs, arriving at the room and blowing open its double doors with an explosive, only to find the suspect lying on the floor in a pool of blood in the room, darkened with its blinds closed tightly. Large guns are strewn about haphazardly. Officers take note of the wires that web through the suite, but relax when they see that they’re linked to an elaborate system of cameras: they see one perched on a service cart outside the room, and another attached over the peephole.

“He has an intricate camera system set up,” one of the first officers to arrive in the suite observes, “so he knew when officers were coming down the hallway.”

The footage, seen publicly for the first time on Wednesday, was recorded on body cameras worn by two of the first police officers to arrive at the hotel suite of gunman Stephen Paddock in the moments after the deadliest mass shooting in modern American history. Paddock killed 58 people and injured hundreds more at a country music festival on a lot nearby from his perch high up in the hotel, then shot himself in the head, officials said. 

The videos are part of a cache of evidence to be made public after a judge sided with media organizations in a legal debate with the Las Vegas police, who had sought to delay the release of the video footage and records because they are part of an ongoing investigation. But media organizations — including The Washington Post — argued in court that the department should have to make public the recordings, 911 calls, affidavits and interview reports.

The cameras capture the human moments of officers responding to a massacre that in previous eras might have been unthinkable; the frantic tone of a police dispatcher shouting “Multiple casualties!” over a radio; the confused looks of gamblers in the hotel lobby as the heavily armed police hustle in; the beads of sweat on an officer’s upper lip as he makes his way towards the gunman’s suite. 

Later, during a lull as officers mill about Paddock’s room, one officer shakes his head and wipes his eye.

“How many did he put down, do you know, downstairs?” he asks another.

“A lot,” the officer wearing the body camera responds.

Though police have released a preliminary report on the shooting, Paddock’s motivation for the meticulously planned attack remains an unsettling unknown. By the time officers from the Las Vegas Metropolitan Police Department Strike Team reached the room, no shots had been fired for about 40 minutes, according to the report.

The Las Vegas police’s report said that authorities still did not know why the gunman carried out the attack, although they ruled out any political or ideological radicalization. He acted alone, investigators said, and left behind no suicide note, manifesto or other explanation.

After some mass shootings, attackers make clear their reasoning, either in confessions to police or in videotaped rants left behind. In other cases, answers remain elusive, leaving victims and their loved ones to struggle with explaining the horror unleashed upon them.

Authorities said the Las Vegas gunman had prepared carefully for the attack as well as the sprawling inquiry that would ensue, saying in court filings that he worked “to thwart the eventual law enforcement investigation.” A search of the gunman’s computers found an Internet search history that included queries for information about outdoor concert venues, SWAT tactics, weapons and the locations of various gun stores. Officials also said they found “numerous” images of child pornography on the gunman’s computers.

Surveillance-camera footage released earlier this year showed Paddock bringing the more than 20 guns and a large amount of ammunition into the 32nd floor room in more than a dozen suitcases.

Joseph Lombardo, the Las Vegas sheriff, has been critical of the fact that police have to release the body-camera footage and other evidence. He said it would be onerous and difficult for the police department to handle the releases and described the footage as harmful to people who were injured in the massacre or lost loved ones.

“We believe the release of the graphic footage will further traumatize a wounded community. For that, we apologize,” Lombardo told reporters during a news briefing Tuesday, during which he did not take questions. “Further victimization is certain to occur and is something we wanted to avoid.”

After a district court judge in Clark County sided with the media outlets and said the records should be released, the Las Vegas police appealed to the Nevada Supreme Court. Last week, the court rejected that appeal.

Lombardo said detectives would have to be reassigned from their main duties to handle the release of the records, adding: “Many of our employees will have to endure reliving the incident.”

The other materials will be made public “on a rolling basis,” Lombardo said. He also said a final report on the police investigation would be published at an unspecified later date and “give context to the different documents that we have been ordered to release.”

Days after the attack, police published harrowing recordings captured by officers’ body cameras that showed the horror unfolding outside as the gunfire began.

Officers are seen scrambling to figure out where the shots are coming from. At one point, an officer is heard saying: “They’re shooting right at us, guys. Stay down! Stay down!”

Images were also leaked that week offering glimpses both inside and outside the gunman’s suite, a disclosure that Lombardo called troubling. When his department released its preliminary findings on the shooting this year, that report included several photographs taken inside the suite. Among them were pictures of the guns stockpiled in the room and a chilling view that the gunman would have had of the concert venue while he fired.

Before Wednesday, the Las Vegas police had released some body-camera footage from the night of the shooting.

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