Las Vegas shooting: What police found in gunman's hotel room

"At least 10 rifles" in Vegas room

Last Updated Oct 2, 2017 7:57 PM EDT

The Las Vegas Metropolitan Police Department used an explosive charge to breach the door and make entry into shooting suspect Stephen Paddock's room on the 32nd floor of the Mandalay Bay Resort & Casino, bringing an end to the deadliest mass shooting in U.S. history.

They found Paddock, 64, dead in the room. He apparently killed himself. They also found "at least 10 rifles" as well as ammunition, confirmed Las Vegas Metropolitan Police Department Undersheriff Kevin C. McMahill by phone Monday on "CBS This Morning."

He said police obtained a search warrant and were going through evidence at the site in a "slow and methodical" manner, watching for booby traps.

Investigators believe the gunman fired through the window of his room and killed at least 59 people who were at the Route 91 Harvest country music festival across the street from the Mandalay Bay. At least 527 others were wounded.

Chaos in Las Vegas as shooter unleashes barrage of bullets

While McMahill could not confirm reports of smoke detectors going off that helped identify Paddock's room, he credited a number of officers at the music festival who were able to hear and see the rounds being fired from Mandalay Bay.

"So a number of responding officers went over there immediately. There was a lot of confusion as you can imagine, so it took a little bit to get to that room, but as soon as they were able to isolate that room and identify it, they did an immediate explosive breach on it, went in, and [Paddock] had shot himself," McMahill said.

Police also served a search warrant at the suspect's home in Mesquite, Nevada. Paddock lived in a retirement community there, about an hour and half northeast of Las Vegas.

"It's just unbelievable. Really, none of it really makes sense," McMahill said. "Trying to see those things that maybe we should have known, maybe we could have caught. Right now, there's no indication of that. A 64-year-old man goes on a homicidal rage, kills over 50 people."

The gunman's brother, Eric Paddock, who lives in the Orlando, Florida, area, said he's was in regular communication with Las Vegas police since the news broke.

"Horrified" brother of Las Vegas suspect says he's "dumbfounded"

He said his brother had no criminal history, no political or religious affiliation, no military background and no history of mental illness.

"If he'd have killed my kids, I couldn't be more dumbfounded," Eric Paddock said.

Investigators in Las Vegas continue working to put pieces of the puzzle together, searching for clues about whether anyone else may have known of Stephen Paddock's plans, and looking at as much video evidence as possible, including security camera footage from Mandalay Bay.

"We trained for this. It's just something you hope is never going to happen. It happen now. Now we need to figure out why," McMahill said.