Bodycam footage has been released showing the moment police blasted their way into the hotel room from which a gunman had just carried out the most murderous mass shooting in modern US history.

Las Vegas officers found Stephen Paddock, who had killed 58 people and injured hundreds more, dead on the floor, surrounded by dozens of weapons, some of which had been modified to inflict as much pain and death as possible.

Hours of footage shot by two officers’ body cameras showed what they discovered when they reached the room. However, analysis of the pictures yielded few clues as to the gunman's motivation, which remains largely mysterious.

They show officers walking into the Mandalay Bay casino, which was still packed with people playing slot machines and drinking, unaware gunfire had been raining down on an outdoor concert from 32 floors above them.

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“You need to get everybody out of here,” an officer tells two security guards. “There’s a shooter up there. He’s killed multiple people already.”

The video shows officers methodically checking rooms on floors 29, 30 and 31, before getting to Paddock’s room on the 32nd floor.

An officer says, “Breach! Breach! Breach!” before a loud bang and a fire alarm begins to sound.

Inside, Paddock’s body is seen on his back, clad in dark trousers and a long-sleeved shirt, with a glove on his left hand. A pool of blood stains the carpet near his head as a police SWAT officer walks past.

Officers in the videos mentioned the number of firearms scattered around the room, with one saying there were at least 10 high-powered weapons.

“Did he have any scoped weapons over there?” an officer asked. “Oh yeah,” another replied.

Mourners attend a vigil to mark the mass shooting at the Route 91 Harvest country music festival (Getty)

Others talked about Paddock “blasting out the window” and pointed to “a whole suitcase full of loaded AK mags,” referring to ammunition magazines for an AK-47 rifle.

Officers are seen looking behind curtains, and one grabbed an assault-style rifle from the ledge of a broken window. An officer told others to watch where they were stepping.

“I don’t know what that is, but there’s a wire there,” the officer said. He then turned towards the room’s door and said: ”He put cameras up on the peepholes and all that. That’s what these wires are.”

An officer said the attacker “has an intricate camera system set up... so he knew when officers were coming down the hallway.”

The videos also record officers talking about whether there was evidence of a second shooter and finding Paddock’s driver’s licence.

Police and the FBI later said they believe the 64-year-old former accountant and high-stakes video poker player acted alone.

The footage does not show what the first officer through the door saw, because he didn’t activate his bodycam. The disclosure raised questions about whether officers followed department policy. The department requires officers with body cameras to activate them during calls that lead to interaction with residents and searches.

The newly released videos, containing around two hours of footage, are a sample of hundreds of hours of bodycam recordings and do not provide a complete view of everything police discovered when they entered Paddock’s suite.

Air Force One departs Las Vegas past the broken windows on the Mandalay Bay hotel, where shooter Stephen Paddock conducted his mass shooting (Reuters/Damir SagoljMike Blake)

Several media outlets sued to obtain videos, 911 recordings, evidence logs and interview reports to shed light on the response by public agencies, emergency workers and hotel officials while Paddock fired for more than 10 minutes.

The police investigation is not finished, the Clark County Sheriff, Joe Lombardo, told reporters, saying he believed releasing the footage would “further traumatise a wounded community.”

“For that, we apologise,” said the elected head of the Las Vegas Metropolitan Police Department. “What is seen on those videos in no way changes the facts that we were able to clarify for you shortly after the crime.”

Mr Lombardo referred to a preliminary police report released on 19 January which said Paddock meticulously planned the attack, researched police SWAT tactics, rented hotel rooms overlooking outdoor concerts and investigated potential targets in at least four US cities.

Police department lawyers had told a judge it would be time-consuming and costly to comply with the media outlets’ public records requests and said the materials could disclose investigative techniques.

But last week, the Nevada Supreme Court upheld a state judge’s ruling that the records must be made public.