As gunfire rained down on thousands of people from the 32nd floor of the Mandalay Bay Hotel and Casino on Sunday, killing nearly 60 and injuring more than 500 more, law enforcement was faced with a significant challenge: how do you find the shooter in a building that reportedly houses 3,309 rooms.  As Stephen Paddock moved between shattered windows, using a bump-fire stock to release rounds at a rate of fire comparable to that of a fully automatic weapon, time was not on law enforcement’s side.

It turns out that it wasn’t the muzzle flash from the windows, which were high enough in the dark Las Vegas sky to make correctly identifying exactly where the shooter was difficult, but rather it was the smoke released by firing so many rounds in rapid succession.  The first indications law enforcement received of where to find Paddock came from smoke detectors that were set off as the gunman continued the massacre.

It took 20 minutes for anyone to find the room Paddock was firing from, far less time than would have required to search each of the 43 floors of concert facing rooms.

The way the shooter was identified was not from the muzzle flashes, but the smoke detector in the room went off from the amount of smoke that came from firing that fully automatic weapon.” Randy Sutton, a former Las Vegas Metropolitan Police lieutenant who was apprised of the situation by active officers told CBS.

It actually wasn’t the Las Vegas SWAT team now believed to be responsible for ending the gunfire, but rather an unnamed security guard who approached the room before police could get there, according to a statement made by Las Vegas Undersheriff Kevin McMahill.  Paddock, who had placed cameras in the hallway as well as at the door’s peep hole, then turned his guns to the door, shooting the security guard.

No further details have yet been released as to the guard’s identity or the severity of his wounds.

It is believed that was the last round Paddock fired at anyone other than himself.  Police quickly used explosives to breach the door, only to find Paddock’s body on the floor, dead by a self-inflicted gunshot wound to the head.

What exactly caused the 64-year-old retiree to go on such a gruesome killing spree remains a mystery at this time, but it has become clear that the crime was not only premeditated, but meticulously planned.  A total of 47 firearms have been recovered from Paddock’s room and home, at least 12 of which had been modified with bump-fire attachments designed to increase the rate of fire possible for each weapon.  According to law enforcement officials, explosives have also been recovered from his vehicle and residence, seeming to indicate that Paddock may have had more destruction planned before choosing to take his own life.