The journey to the room at the end of the 32nd floor began at the switchboards of the Mandalay Bay Resort and Casino, a tropical fantasy in the Nevada desert.

As the noises began, scores of confused guests pressed zero on their room phones almost all at once. The first callers asked about what sounded like a sustained burst of fireworks. Others wondered: Was it something else? The hotel operators realized that for callers on some floors, the popping was louder than for guests phoning in from others.

Outside the hotel entrance, Las Vegas Metropolitan Police officers were pinned down along South Las Vegas Boulevard, searching for the origin of what they knew was a barrage of gunshots. Someone had been firing into a crowd of country music fans at a venue across the street. Muzzle flashes had been visible halfway up the hotel’s north tower — a clue that then disappeared.

“Haven’t seen any flashes,” an officer said over the radio at 10:22 p.m. Sunday. “There is a strobe light from one of those windows.”

Steve Sisolak, chairman of the Clark County Commission, said it was clear that the shots were coming from the Mandalay Bay and that the flashes were coming from the windows facing the Strip, but that was about all: “They knew he was up there, and they didn’t know where.”

Almost exactly an hour after those observations, a SWAT team burst into Stephen Paddock’s room and found the 64-year-old retired accountant dead; he had shot himself in the mouth with a handgun after spraying the concert crowd with bullets, killing 58 people and wounding more than 500. The raid ended a search that drew on the geometry of Paddock’s frantic attack and the evidence gathered by the hotel’s operators, who narrowed down his location based on the calls coming from frightened guests.

The Mandalay Bay Resort in Las Vegas. One of the windows Stephen Paddock broke out can be seen along the right side of the tower. (The Washington Post)

Police believed at one point that there might have been as many as three attackers, then “confirmed” at least two. The volume of Paddock’s fire made implausible the idea that one man was behind it. But in the end it was just Paddock, his motive still a mystery, a man who had taken extraordinary steps to monitor the progress of the raid on his room — a raid he knew would be coming.

Two people close to the investigation said Paddock set up remote video cameras, which streamed images through a tablet so he could see down the hall behind him as he fired into the audience below. Police found one camera on a room-service cart parked in the hallway awaiting pickup.

Probably alerted by the images of police approaching his suite at the end of a long hallway, Paddock fired numerous rounds through his door, hitting a hotel security guard who was clearing guest rooms one by one.

The guard, whose name has not been released, was wounded in the leg by shrapnel kicked up from a ricocheting bullet, which did not hit him directly. The police radio crackled soon after: “Mandalay security says shooter is on 32nd floor, they have security officer on that floor who was shot.”

Questions since the shooting, the worst in modern U.S. history, have focused in part on the adequacy of hotel security. Paddock managed over several days to assemble an arsenal of 23 firearms in his room, many of them rifles, apparently bringing them up in 10 suitcases. Police and hotel security took more than an hour to find Paddock after he began firing.

But there is much about this city’s confectionery skyline that appears designed specifically for someone who does not want to be found. The sheer scope of the Strip’s most popular hotels is chief among those features.

With three wings and more than 3,200 rooms, the Mandalay Bay stands as a primary example of the city’s architecture of anonymity, the relatively tiny black holes Paddock punched through the reflective gold-glass facade evidence of the security staff’s needle-in-a-haystack endeavor.

The search for his room began amid 11 minutes of sustained volleys of gunfire that scattered the 22,000 people at the Route 91 Harvest festival in an open-air concert ground across the street from the 40-story-plus Mandalay Bay.

“We need to stop the shooter!” an officer said over the radio just after 10:17 p.m. “He’s firing right over our heads!”

Inside his room on the 32nd floor, Sonny Morgan, in town from Georgia for a conference, dozed in front of the "Sunday Night Football" game. "I woke up to the sounds of gunshots," Morgan recalled in an interview with WXIA-TV in Atlanta. "Initially, I had kind of thought that it may have been some fireworks . . . and then it just kept going and going and going."

He called reception and was told to barricade himself inside his room.

Then, after the furious initial barrage, the shooter paused.

This video shot by a tourist in January 2016 apparently shows the inside of room 32-135 of the Mandalay Bay hotel in Las Vegas. On Oct. 1., Stephen Paddock used the room as a base to shoot and kill at least 58 people.

For about three minutes, Paddock stopped firing, leaving officers who were trying to track the trajectory of the shooting with little to go on. An officer commented just after 10:20 p.m., “Been a while since we heard shots.”

A little more than a minute later, Paddock opened up again. “We are taking fire here!” one officer said, according to the radio transcript. “Advise officers do not go up on the boulevard.”

One officer spotted what he described as a “strobe light” coming from midway up the hotel’s north tower.

At the time, Mandalay hotel security and the Las Vegas police were sorting through officer observations about the trajectory of the shots and what they were learning from the guest calls coming into the call center. Police officials say they concluded that the shooter was firing from a room between the 29th and 32nd floors.

Security guards and police officers began clearing those floors, believing at the time that as many as three shooters might have been involved.

At about 10:27 p.m., as officers outside began setting up a medical triage center at the nearby Tropicana Hotel amid continuing gunfire, the Mandalay security officer made his way down the hall on the 32nd floor toward the room at the end.

Paddock, according to investigators and the radio transcript, gave himself away by firing through the door, but police were still convinced he was not alone.

“Have confirmed that there are two shooters with fully automated weapons,” an officer said, according to the transcript, about a minute after the hotel guard was wounded.

From that moment on, though, the room at the end of the hall went quiet.

On the Strip outside, police officers were securing their patrol cars after reports that private citizens had been grabbing shotguns from them for protection.

Reports of shots fired at hotels north of the Mandalay — at the Luxor next door, at the Bellagio a mile up, at several others — commanded police attention. A man dressed in fatigues was tracked to an RV outside the Tropicana, and police moved in with shotguns.

The reports of gunfire in other hotels proved unfounded, the man in fatigues a harmless distraction.

Inside the hotel, the police moved toward Paddock, who had stopped firing.

“Moving up to the 32nd floor,” an officer said on the radio about a half-hour into the attack.

A minute later, from another officer, “Can confirm that there is no gunfire?”

“We’ve been here for the past [unclear] minutes and haven’t heard gunshots for oh, probably 15 minutes,” came the response.

Two minutes later: “We are covering the stairwell on 32.”

For the next half-hour, the SWAT team prepared for the raid. Morgan, the conference attendee, recalled in his interview with the Atlanta TV station, “I could hear the police making their way up the hallway, and they were basically breaking down the doors — opening the doors aggressively.

“Six or seven SWAT guys came in and just made sure that I wasn’t a bad person — that I was doing what I was supposed to be doing,” he said. “They ushered us out and told us to run as far and as fast as we could to get away.”

At about 11:25 p.m., the floor cleared except for the room at the end of the hall, a senior officer announced over the radio: “We are gonna set off outside the suspect’s door. We are gonna pop this and see if we get any kind of response from this guy.”

“SWAT has explosive breach,” the dispatcher responded. “All units move back.”

The raid did not last long. SWAT team members found Paddock on the floor, blood spilling from his mouth and pooling around his head.

Video from the hallway shows a room-service cart, probably the one in which Paddock placed a camera. Briefing reporters here Tuesday, Sheriff Joe Lombardo said room service did come to Paddock’s room. But he did not disclose at what time.

Lombardo praised the hotel security response, saying, “We would not have engaged this individual in the time lapse that we did without their assistance.”

“Were it not for the men and women of the police department and the security at Mandalay Bay to help triangulate that movement and get to the 32nd floor, the casualty toll would not be 59 people but in the hundreds,” Sisolak, the Clark County commissioner, said. “They saved hundreds of lives by their actions to find that room on the 32nd floor.”

Devlin Barrett and Ann Gerhart in Washington contributed to this report.