LAS VEGAS -- The New York Times has developed a new timeline of the mass shooting in Las Vegas by piecing together evidence from videos taken at the scene.

The New York Times investigation says the shooting started at 10:05 p.m. local time, matching the investigators timeline, and after some initial single shots, automatic gunfire can be heard with country singer Jason Aldean on stage.

But at 10:06 p.m., one minute into the attack, the Times says Stephen Paddock shoots Mandalay Bay security guard Jesus Campos in the hallway. This contradicts investigator's latest timeline, which said Paddock first shot Campos and then began to shoot into the crowd uninterrupted.

Malachy Browne CBS News

It's one of many questions being raised by a team of digital investigators at the Times, which used 30 videos to create a timeline.

"Ours isn't the definitive picture of what happened, more information will emerge, but it does give us new insights into what happened," says Senior Story Producer Malachy Browne. "We analyzed every single burst of gunfire, which had its own fingerprint."

Thirty-six seconds after Campos radioed in came a second round of automatic gunfire into the crowd of the Route 91 Harvest Festival.

There is just a 17-second lull before a third burst of gunfire, and only 20 seconds later, a fourth burst.

The Times counts more than 900 rounds were shot into the crowd.

At 10:10 p.m., muffled gunfire is heard from a taxi driver's cellphone video, indicating that the shooter might have been firing into the hallway again.

What's unclear is why officers wouldn't arrive on the 31st floor for another two minutes, and not until 10:22 p.m. to the 32nd floor --a full seven minutes after the shooting started.

Taxi driver Corey Langdon questions why there are no officers -- or panic -- outside Mandalay Bay.

"Everybody's just standing around," Langdon said.

More than three weeks after the shooting there are still many unanswered questions. What was Paddock's motivation? Why did he allegedly shoot himself and why are there still so many questions about the timeline?

CBS News reached out to the sheriff's office, who's the lead investigator in this case. They said there is no investigative update at this time.