(CNN)After Stephen Paddock opened fire on concertgoers from his hotel room in Las Vegas in October, officers stealthily moved down the hallways with guns drawn, ordering hotel occupants to stay indoors.
Bodycam video shows tense moments as police entered Las Vegas killer's suite
"Lock the door, your door was open. There's someone shooting inside the casino!" an officer warns people in one room as they sweep the Mandalay Bay Resort and Casino.
Officers go to several floors, warning people in the lobby and hallways to take shelter or flee. Shortly after, they arrive at the gunman's hotel suite on the 32nd floor.
"Breach. Breach. Breach!" an officer says before a loud blast rings out. Some officers cover their ears with their hands as the explosion rips apart the doors to the gunman's suite.
Police stormed his room and found the gunman dead from a self-inflicted gunshot wound.
Paddock killed 58 people and left hundreds more injured on October 1, when he shot indiscriminately at concertgoers attending the Route 91 Harvest Festival. It became the deadliest mass shooting in modern US history.
His motive remains unknown.
The Las Vegas police released nearly three hours of body camera footage for the first time Wednesday, providing details on the officers' actions after the shooting.
The footage captured the moments before and after they entered the gunman's room. At one point, an officer asks how many people the shooter killed.
"A lot," another officer responds.
The footage was released after several media organizations, including CNN, argued that police information on what happened that night should be released. The Nevada Supreme Court ruled Friday that police should release the bodycam footage and 911 calls from the shooting. Police had appealed an earlier ruling that called for the material be released.
Sheriff Joe Lombardo of the Las Vegas Metropolitan Police Department said video footage, 911 call audio and documents relating to the massacre would be released on a rolling basis. They started with the body camera footage from two officers.
The first officer to enter the room did not have his body camera on, according to the Las Vegas Review-Journal.
The footage begins inside an officer's squad car shortly after the shooting. As the driver rushes to the scene, police radio traffic in the background describes the unfolding carnage.
One video clip shows when police approached Paddock's door, it was blocked by a room service cart.
One officer notices a device at the door. "Looks like it might be a camera of some sort," the officer can be heard saying.
As more officers rush past, others urge caution.
"Hold on, hold on," another officer says.
As officers enter the suite, they see more cameras pointing down the hallway. The officers can be seen clearing the suite room by room, using dogs to search under the bed and in closets.
In a news briefing Tuesday, Lombardo cited cost, allocation of resources and further victimization of those affected by the shooting as reasons for delaying the release of the footage, recordings and documents.
The department had to reassign detectives from their "primary responsibility" to go over the reports and footage before they were made public, making some relive the shooting all over again, he said.
"I want the community to know the release of the videos, 911 and documents will have a significant impact on the victims of this tragedy. We believe the release of the graphic footage will further traumatize a wounded community," he said. "And for that, we apologize."
Lombardo said no employees will be made available for interviews, adding that a final comprehensive report on the shooting will be released.
Police were criticized about their response when a timeline suggested there had been a six-minute delay between Paddock shooting a security guard and the gunman opening fire on the crowds below his hotel suite.
The timeline raised questions about why police didn't arrive on the scene sooner.
"In the public space, the word 'incompetence' has been brought forward. And I am absolutely offended with that characterization," Lombardo said on October 13.
He said that during the six-minute gap, the security guard had been trying to access Paddock's room -- and that he was shot around the same time the gunman started firing on concertgoers.
"So there is no conspiracy between the FBI, between the (Las Vegas Metropolitan Police Department) and MGM (the hotel owner). Nobody is attempting to hide anything in reference to this investigation," Lombardo said at the time.
"The dynamics and the size of this investigation requires us to go through voluminous amounts of information in order to draw an accurate picture."