More details revealed about Las Vegas shooter's arsenal of weapons

The gunman who opened fire on a crowd in Las Vegas had an arsenal of weapons worth tens of thousands of dollars, with at least one made-to-order firearm from built by a high-end manufacturer.

Stephen Paddock, who killed 58 people at a concert from his hotel room on the 32nd floor of the Mandalay Bay casino, was found dead in his hotel room with 24 weapons, including at least 12 semi-automatic rifles outfitted with "bump stocks" to increase their rate of fire. He purchased 33 weapons between October 2016 and Sept. 28 of this year, when he checked into the Vegas suite. Investigators found thousands of rounds of ammunition in addition to the weapons in his hotel room, as well as several dozen more firearms in his residence in Mesquite, Nevada.

A law enforcement source tells CBS News senior investigative producer Pat Milton that some of the weapons recovered by investigators were high-quality, expensive firearms with custom-made add-ons including scopes. 

At least one of the weapons was a made-to-order firearm made by Lewis Machine & Tool Company (LMT), the source said. LMT is a specialty guns manufacturer that provides weapons to the U.S. military and law enforcement agencies, according to the company's website. Individual made-to-order weapons can cost several thousands of dollars, depending on the add-ons included. LMT did not immediately respond to a request for comment.

Paddock was a frequent gambler and multimillionaire who earned much of his fortune through real estate investments, according to his brother Eric Paddock. He began purchasing firearms in 1982 and had purchased more than 50 legally, according to Jill Snyder, special agent in charge at the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).

Snyder told "CBS This Morning" co-host Norah O'Donnell that Paddock's purchases didn't set off any alarms at the ATF. 

"We wouldn't get notified of the purchases of the rifles," Snyder said. "We would only get notified if there was a multiple sale, which would be two or more handguns in an individual purchase." 

Snyder said there is no federal law requiring notification of sales of multiple semi-automatic rifles.

Christopher Sullivan, the general manager of Guns & Guitars in Mesquite, told CBS News correspondent DeMarco Morgan that he sold Paddock a rifle on Sept. 28, the same day he checked into the Mandalay Bay hotel in Las Vegas. Sullivan said Paddock had been a customer for about a year, and in that time the shop sold him five firearms.

"This morning over coffee I was having a moment in myself thinking that I may have very well been the last person to shake hands with that man,'" Sullivan said.