10:19 p.m.

“While there was that slight delay, the suspect was no longer firing into the crowd.” — Kevin McMahill, Las Vegas Metropolitan Police Department undersheriff

It remains unclear why Mr. Paddock did not fire more rounds, or when he turned one of his guns on himself.

But it would take more than an hour after the shooting stopped, until 11:27 p.m., for a SWAT team to burst through the Vista Suite’s door after two breaching attempts.

As the SWAT team was arriving, the authorities were evacuating guests from their rooms, starting from the 29th floor, where some officers apparently thought one gunman might be. On the 32nd floor, where Mr. Paddock had been staying, some guests left their rooms and ran down the hallway to the elevators in bare feet. Even as police officers closed in on Mr. Paddock’s room, however, uncertainty persisted about whether he was the only gunman.

“It sounds like it’s confirmed there are at least two shooters with fully automatic weapons,” an emergency responder said on the scanner at 10:27 p.m. The scanner also crackled with false reports of shots at other hotels. Some officers did not know for hours whether the festival area was secure.

“I was hearing traffic on the radio all night about shots at the Tropicana, shots at Caesar’s,” said Travis Smaka, a trooper with Nevada Highway Patrol. “Shots were being reported everywhere, it was impossible to know what was really going on. People were going in every direction and victims were all over. I spent the whole night thinking we were under attack.”

But the threat was just Mr. Paddock, and he had stopped shooting. Several emergency responders remarked in the minutes after 10:19 p.m. that they had not heard any shots in some time.

The closest major trauma center, Sunrise Hospital and Medical Center, received word of the shooting from the police at 10:20 p.m., and activated its mass-casualty system one minute later.

On Tuesday evening, Mr. McMahill was defensive as he described the period between the final shots and the SWAT team’s arrival. “While there was that slight delay, the suspect was no longer firing into the crowd,” he said.

With the floor secured and Mr. Paddock isolated by 10:58 p.m., according to audio from the police scanner, a SWAT team exploded two door-breaching devices, then broke in at 11:27 p.m. They found Mr. Paddock, dead of what seemed to be a self-inflicted gunshot wound, lying on the carpet among his guns, shell casings and ammunition.