ROBYN BECK/AFP/Getty Images(LAS VEGAS) — The first report from a maintenance man that a gunman was firing down the hall of the 32nd floor of the Mandalay Bay hotel was not relayed to Las Vegas police until after the gunman had already begun his deadly rampage on the concert audience below, according to a person who has reviewed the records and spoke to ABC News on the condition of confidentiality.

Officials estimate the hotel’s delay in reporting the incident in which a hotel security guard was shot lasted about six minutes. But in a statement, hotel officials say that timeline “may not be accurate.”

The new details of the moments before the deadliest mass shooting in modern American history came as the lawyer for one victim began asking the first uneasy questions as part of what is expected to be a rash of victims’ lawsuits focused on the initial response by Mandalay Bay casino officials.

“Was 911 called? The whole chain of command seemed to be broken down here,” said Mohammed “Mo” Aziz, a lawyer hired by shooting victim Paige Gasper. “For six minutes nothing happened, and then this criminal started shooting at innocent people.”

The lawyer’s questions Tuesday have put a new focus on the still-murky timeline for the moments leading up to the shooting. The shifting accounts from authorities first indicated a casino security guard was the last person to be shot before the shooter took his own life. Then they said he was the first to be injured. Now the sheriff says the timeline is being revised yet again.

Sources close to Mandalay Bay told ABC News Tuesday the response by casino staff was swift and saved lives. The first call from hotel, the sources said, did not go out to police until after the rampage was underway – about six minutes after the initial hallway confrontation. And officers did not reach the 32nd floor suite of retired commercial property owner and frequent gambler Stephen Paddock until after the shooting had stopped.

New audio recordings made public by the hotel’s corporate owner, MGM Resorts, capture the moments when a hotel maintenance man, Steve Schuck, called in the first report of trouble.

“Call the police,” Schuck tells hotel security. “Someone’s fired a gun up here. Someone’s fired a rifle on the 32nd floor down the hallway.”

But neither the police account of the ensuing moments nor publicly transmitted police radio traffic indicate when the hotel security office dialed 911.

Approximately six minutes after Schuck made the request for help from police, Paddock began pouring rifle fire on concertgoers down on the Route 91 country music festival, 32 floors below. Officers did not reach the 32nd floor until at least 18 minutes after security guard Jesus Campos was shot in the thigh, and they appeared to have no idea he had been wounded at all before finding him.

“They weren’t aware of him being shot until they met him in the hallway after exiting the elevator,” said Clark County Sheriff Joseph Lombardo.

“We have a security officer also shot in the leg on the 32nd floor. He’s standing right by the elevator,” a Las Vegas Metro policeman radioed, in a recorded transmission 20 minutes after Campos was hit by Paddock’s gunfire.

Assistant Sheriff Tom Roberts told reporters Monday that police are still studying the timeline, but he does not think the lag was long under the circumstances.

“I don’t think the delay, or the time lapse is that long — in my opinion,” Roberts said. “I think the security guard saved a lot of lives — he interrupted this guy and sped up his plan, in my opinion.”

In part, the response time may have been slowed by a decision to shut down the elevators, a move by hotel management described by Schuck in an NBC News interview. Some police had to climb an unknown number of flights of stairs carrying weapons and body armor.

At 10:16 p.m., an officer radioed his dispatch to “contact Mandalay Bay and have ’em shut down their elevators so he [the gunman] can’t get mobile and we can take the stairs and block all the stair exits.”

One officer was later heard on police radio traffic breathing heavily and announcing he’d made it up to the same level the gunfire was erupting from. “I’m in a stairwell on the 32nd floor,” he says in a hushed voice.

Sgt. Mike Quick, a retired Las Vegas SWAT team veteran, said the Mandalay Bay is a sprawling property, with a number of impediments. “That’s a 3,000-plus room casino hotel, I mean that’s a major resort eating up acres and acres of property. So just parking and getting through the front doors is going to be an exercise in time.”

Marshalling an elevator could have taken time, he said. But climbing the stairs was an “extreme challenge.”

MGM Resorts spokesperson Debra DeShong issued a statement Tuesday in response to the lawsuit filed on behalf of Paige Gasper.

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