Las Vegas police on Wednesday released dramatic body-camera video from the deadliest mass shooting in modern U.S. history.

The footage shows the tense moments when a group of heavily armed SWAT officers entered the 32nd-floor hotel room at the Mandalay Bay where Stephen Paddock unleashed gunfire on a concert last October.

Police and the FBI have said he killed 58 people and injured hundreds more before killing himself as authorities closed in.

The footage will not show what the first officer through the door saw because he didn't activate his body-worn camera.

Las Vegas police on Wednesday released some officer body-camera video from the deadliest mass shooting in modern U.S. history

The footage shows the tense moments when a group of heavily armed SWAT officers entered the 32nd-floor hotel room at the Mandalay Bay where Stephen Paddock unleashed gunfire on a concert last October

In the video a loud bang is heard before officers slowly move into the room where Paddock was staying

Indeed, during the footage the jangly music of slot machines can be heard echoing through the packed room as police officers methodically made their way across the casino floor with their guns drawn.

But the hustle and bustle of Las Vegas went on and gamblers just continued tugging at slot handles, seemingly unaware that just upstairs a man was unleashing a hail of gunfire in the deadliest mass shooting in modern U.S. history.

'There's a shooter! He's shot and killed multiple people already,' a police officer shouts as he passes bystanders, on the hunt for the man who killed 58 people from his high-rise hotel suite.

The officers carefully work their way up to the 32nd floor of the Mandalay Bay casino-hotel. As they approach his suite from a stairwell, another officer yells out, 'Breach! Breach! Breach!' before a loud bang and a fire alarm begins to sound.

Officers search hallways as the approach Stephen Paddock's suite in the Mandalay Bay hotel

This photo from police officer video body camera footage shows officers as they breach the shooter's room

Preparation: Las Vegas Police move in on Paddock's room armed with tactical shields

Inside, they find Stephen Paddock lying in a pool of his own blood with rifles strewn about. One officer pulls a high-powered rifle from a window ledge as the other officers discover an arsenal of weapons, cameras in the peepholes, a homemade gas mask and venting system and even a vibrator.

But more than seven months after the Oct. 1 massacre, police are no closer to answering the key question in the investigation: What led the retired accountant and high-stakes gambler to unleash his deadly barrage of bullets?

The videos showed officers inside Paddock's room looking behind curtains, and one grabbed an assault-style rifle from the ledge of a broken window. The gunman's body is seen on his back, clad in dark pants and a long-sleeve 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 noted the amount of firepower Paddock had — more than 10 high-powered firearms. Others talked about Paddock 'blasting out the window' and pointed to 'a whole suitcase full of loaded AK mags.'

Investigators believe the 64-year-old acted alone in the attack and fatally shot himself before officers burst through the door of his hotel suite.

The body camera video that was released on Wednesday, which totals about 2½ hours, represents a sample of hundreds of hours of body-camera recordings and does not provide a complete view of everything police discovered when they entered Paddock's suite.

The footage doesn't show what the first officer through the door saw because he didn't activate his body camera.

The revelation that the officer failed to activate his camera 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 represent a sample of hundreds of hours of body-camera recordings that don't answer why Paddock opened fire, Clark County Sheriff Joe Lombardo told reporters Tuesday

The footage will not show what the first officer through the door saw because he didn't activate his body-worn camera

The room is dimly lit. The video does not show Paddock or his extensive arsenal of weapons that were later found in his room

The Associated Press and other media outlets sued to obtain videos, 911 recordings, evidence logs and interview reports

In October, just days after the shooting, police released body cam footage showing Paddock's dead body after he took his own life

Paddock shot himself in the head after committing the massacre and is seen lying in a pool of blood on the floor of the Mandalay Bay hotel suite

That disclosure by police lawyers late Tuesday raises questions about whether officers followed department policy.

The newly released videos represent a sample of hundreds of hours of body-camera recordings that don't answer why Paddock opened fire, Clark County Sheriff Joe Lombardo told reporters Tuesday.

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

The police investigation was not finished, said Lombardo, who oversees the department and called the preparation and release of documents sought by the media a 'monumental task' that would divert resources from police work.

Police and the FBI have said they believe Paddock, a 64-year-old former accountant and high-stakes video poker player, acted alone

Paddock broke two windows in his Mandalay Bay hotel room and then opened fire on 22,000 attending a concert. Fifty-eight people were killed and 527 injured

Photos leaked days after the shooting show several assault rifles strewn across the room, which is littered with spent bullet casings. Behind the pillar above, neat piles of stacked magazines are seen

'What is seen on those videos in no way changes the facts that we were able to clarify for you shortly after the crime,' he said.

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

The sheriff's top spokeswoman, Carla Alston, said Wednesday that no one in the agency would comment about whether the first officer through the door followed proper procedure by not activating his camera or whether he had been disciplined for violating policies.

The Police Department requires officers to activate body cameras during calls that lead to interaction with residents and searches.

The Associated Press and other media outlets sued to obtain videos, 911 recordings, evidence logs and interview reports.

Lombardo said the department would release more records in batches in coming weeks.

'We believe the release of the graphic footage will further traumatize a wounded community. For that, we apologize,' he said.