Members of the law enforcement team who were the first to enter Stephen Paddock's hotel room after he opened fire on a crowd in Las Vegas. Top row, from left to right: Las Vegas Metropolitan Police Department Detectives Casey Clarkson and Matthew Donaldson. Bottom row, left to right: David Newton from the Las Vegas Police Department's K-9 unit and Sgt. Joshua Bitsko. CBS News / "60 Minutes"

A note found in the hotel room of the man who shot into a crowd from his perch in a Las Vegas high-rise included hand-written calculations about where he needed to aim to maximize his accuracy and kill as many people as possible.

In an interview airing Sunday on "60 Minutes," three police officers who stormed Stephen Paddock's hotel room in the Mandalay Bay hotel tell correspondent Bill Whitaker new details about the deadliest mass shooting in modern American history. The officers were the first to see Paddock's body and the arsenal of weapons and ammunition he had stockpiled.

Officer David Newton from the Las Vegas Police Department's K-9 unit said he noticed a note on the shooter's nightstand once officers breached the room. He said the note was located near one of the windows that Paddock had smashed with a hammer to fire onto the crowd below with high-powered semi-automatic rifles outfitted to increase their rate of fire.

"I could see on it he had written the distance, the elevation he was on, the drop of what his bullet was gonna be for the crowd," Newton said. "So he had that written down and figured out so he would know where to shoot to hit his targets from there."

Paddock's hotel suite was on the 32nd floor of the hotel, looking down on the crowd across the street. More than 20,000 people were attending the Route 91 Harvest Music Festival when Paddock opened fire. The crowd was approximately 400 yards away, well within range of the expensive custom-made rifles found in his suite.

Newton told Whitaker what it was like to enter the room amid the flashing lights of a fire alarm set off by an explosive used to blow through the door.

"Very eerie. Yeah, the dust from the explosive breach. And then you have the flashing lights," Newton said. "And that looked straight, like, out of a movie, you know?"

Whitaker spoke to the team in their first in-depth interview and to Clark County Sheriff Joseph Lombardo for a story to be broadcast on "60 Minutes" this Sunday, Oct. 8, at 7 p.m. ET/PT on the CBS Television Network.