Las Vegas police say gunman Stephen Paddock had an escape plan

Police in Las Vegas now believe the man who carried out the deadliest attack on American soil since 9/11 had an escape plan and they are not ruling out possible accomplices. Clark County Sheriff Joseph Lombardo says Stephen Paddock must have had some help, but the gunman's motive is still a mystery.

More than 100 law enforcement agents have been scrutinizing Paddock's life to see what could have led him to open fire on a country music concert Sunday night, killing 59, including himself, and injuring more than 500 others, reports CBS News' Vladimir Duthiers. Paddock also had explosive materials in his car, according to police. 

Investigators looking into the worst mass shooting in modern U.S. history have produced a profile of a gunman that Lombardo called "disturbed and dangerous." 

"What we know is that Stephen Paddock is a man who spent decades acquiring weapons and ammo and living a secret life," Lombardo said.

As "CBS This Morning" co-host Norah O'Donnell reported Tuesday, Paddock began amassing the bulk of his arsenal in the last year – buying a gun just three days before the shooting.

"From October 2016 to September 28, 2017, he purchased 33 firearms, majority of them rifles," said ATF special agent in charge Jill Snyder.

Asked if police are looking into mental health issues or whether something happened in October 2016 to compel him to begin buying weapons, Lombardo said, "Yes."

Paddock left no suicide note and so far his motivation is unclear. CBS News has confirmed aviation fuel tanks located about 500 yards from the concert venue were hit by bullet fire -- but not penetrated. It's unclear whether Paddock targeted the tanks.

He also said Paddock intended to evade capture and survive, but minutes after the shooting began, a hotel security guard showed up outside his suite. Paddock fired well over 200 rounds into the hotel hallway, hitting the guard in the leg.

"His bravery was amazing because he remained with our officers, provided them with a key pass to access the door and actually continued to help them clear rooms," Lombardo said.

The weekend before the shooting, Paddock rented a room in another Las Vegas hotel, the Ogden.  Police don't know why, but the hotel is near where the Life Is Beautiful music festival was held.  Chance the Rapper, Muse, Lorde and Blink 182 were all performing there.