LAS VEGAS • Stephen Paddock used a 32nd-floor suite in the luxurious Mandalay Bay Resort and Casino overlooking the Vegas Strip as a place to scan the crowds at a country music festival and then open fire - leaving at least 59 people dead and hundreds more injured in a rain of bullets or trampled in the panicked rush for cover. He then killed himself as police closed in.
The massacre was possibly in the planning stages for days, said investigators, as they struggled with a chilling but baffling array of clues yet were still left trying to grasp what caused a 64-year-old retiree to turn a concert ground into a killing field.
Police said Paddock arrived last Thursday at the Mandalay Bay Resort and Casino overlooking the Vegas Strip. He aroused no suspicion from hotel staff as he surrounded himself with stunning firepower in two rooms: 23 guns, some with scopes. One of the weapons he apparently used in the attack was an AK-47 type rifle, with a stand used to steady it for firing, people familiar with the case said.
Investigators believe at least one of the guns functioned as if it were fully automatic, and they are now trying to determine if he modified it or other weapons to be capable of spitting out a high volume of fire just by holding down the trigger, people familiar with the case said.
Investigators also found at least 19 additional firearms, thousands of rounds of ammunition and the chemical tannerite, an explosive, at Paddock's home in Mesquite, Nevada. They also found ammonium nitrate, a chemical that can be used in bomb-making, in Paddock's vehicle, said Clark County Sheriff Joseph Lombardo.
Police and hotel security ultimately scoured several floors of the hotel looking for the shooter and came upon Paddock's suite, Sheriff Lombardo said. At some point, Paddock fired through the door and hit a security guard in the leg, he said, adding that the guard is expected to survive.
Swat officers ultimately stormed the room and some fired shots, though Paddock is believed to have killed himself, Sheriff Lombardo said. Paddock was not counted in the death toll.
President Donald Trump ordered flags to be flown at half-staff and said he would visit Las Vegas today. He praised the "miraculous" speed with which local law enforcement responded to the shooting.
Mr Steve Sisolak, Clark County Commission chairman from Las Vegas, praised the police for their quick response and commended the outpouring of support from the community: More than 25,000 people have donated to a fund-raising effort for victims and people have been waiting eight hours in line to donate blood, he said.
"Las Vegas will never be quite the same as a result of this," Mr Sisolak said. But, he said, "we'll be back".