Transcript for More details revealed on Vegas gunman's arsenal
Authorities recovering 47 firearms including that startling arsenal found in his hotel room. ABC's Matt Gutman is in las Vegas with more on that side of the story. Good morning, Matt. Reporter: Hey, good morning, robin. Still activity here, but that arsenal you mentioned is just part of a chillingly meticulous plan put together by Stephen paddock which included weapons modified into machine gun, thousands of rounds of ammunition and something we haven't seen before, surveillance cameras set up outside the room to monitor the approach of law enforcement. This morning a glimpse of the sniper's nest where 64-year-old Stephen paddock stretched several minutes of shooting into what seemed an endless slaughter. We know now that he fired off and on for somewhere between nine and 11 minutes. We know that the suspect fired over a dozen or so volleys. Reporter: These new images revealing a fraction of paddock's total arsenal. 47 firearms have been recovered. These firearms were recovered from three different locations. Reporter: The armory inside that 32nd floor luxury suite included shotgun, pistols and assault rifles. That gray magazine clip you see, able to hold up to 100 bullets. Spent casings littering the floor and chillingly stacked like bricks in the corner at least a dozen more magazines. Experts tell ABC news this image alone shows up to 1600 rounds. And this morning we learn it was a hotel security guard who may have stopped the slaughter. He was advancing towards the room when the suspect fired through the door at the security guard and struck him. He was able to provide additional information to the police on exactly which room we were looking at. Reporter: Police say paddock was able to shoot the guard through the door because he saw him coming. This video showing that room service cart and under a plate the shooter hiding a surveillance camera. Another set up inside the room. That wounded security guard providing crucial intelligence to S.W.A.T. Teams who about an hour later breached that door. Breach, breach, breach. Reporter: They found paddock's body splayed next to his guns shuttering himself inside for three days andchecked in with ten bags. Walking right past this sign. He was perched high above the route 91 harvest festival. ???- Waiting till shortly after this rendition of "God save America" to open fire. Overnight paddock's brother's family releasing this statement. There is just no way to express our shock, devastation and sorrow for all the victims and their families' unimaginable loss. Now hotels on the strip increasing security. On Monday lines stretching outside the Wynn resort as guards screened luggage and scanned visitors with metal detectors and the gaming control more put security guards inside casinos for added security. And we are now learning that Stephen paddock back in June was prescribed 50 pills of valium. It's an anti-anxiety si medication and probably certain that law enforcement is going to examine very closely his mental state leading up to this attack. Robin. So much more to come. Okay, Matt, thank you. Absolutely, thank you, robin.
This transcript has been automatically generated and may not be 100% accurate.