He was a quarter of a mile away and a few hundred feet high — the smallest of specks in a boisterous landscape.
They were 22,000 targets in an open field, dodging gunfire on a night when music turned to madness.
Some staked their lives on the shelter of a beer cart, a food truck, a cooler. Those who ran had little sense of direction. Were they racing toward the shots? Would a car, a restaurant, a hotel closet, become refuge or a trap?
The mass shooting at the Route 91 Harvest Festival would leave 58 dead and hundreds more injured.
It would also highlight the vulnerability of those in the focus of a sniper as well as the chilling limitations of responding officers.
Authorities have long discussed the threat of terrorism by a sniper in a crowded area and the reality that there are relatively few tools to prevent or quickly stop such an attack.
Los Angeles police have tried different tactics, including placing sharpshooters on rooftops during the Academy Awards. Earlier this year and for the first time, the LAPD had a police officer in a helicopter shoot a suspect who was firing from the top of a hill.
But replicating those tactics more commonly at open-air events would be costly and in some cases impractical.
Stephen Paddock’s position — a window on the 32nd floor of the Mandalay Bay hotel — gave him “commanding terrain,” said Charles Heal, a retired Los Angeles County sheriff’s commander and special weapons leader.
“There were so many people in his line of fire, he didn’t need to target anyone,” Heal said. He noted that the complexity of a high-rise hotel created a maze for police attempting to track Paddock.
“If you don't find cover, given his position, he is likely to hit you.”
The scene was sustained by what could be called the trigonometry of terror.
Retired Army Lt. Col. Arthur B. Alphin said Paddock was a patient, well-trained gunner who did not pick and choose his targets, but held to a steady kill zone centered in the middle of thousands of concertgoers.
“He had a huge area of three, four or five football fields with people standing shoulder to shoulder,” said Alphin, who has a mechanical engineering degree and specialized in ballistics.
“He was not aiming at any individual person. He was just throwing bullets in a huge ‘beaten zone.’ ”
Beaten zone is an infantry term dating to World War I. Shaped like the area a searchlight casts across a flat surface, it refers to where bullets can strike. It can move substantially with tiny changes in the tilt of the gun.
From his perch, Paddock was firing down the hypotenuse of a right triangle and would have to adjust his aim for the arc of the bullet — a skill that would require training.
At least one of the 23 weapons found in his hotel room had a bipod stand to hold it steady, authorities said.
Officers on the ground would be virtually ineffective when combating a sniper so far away, said San Marino Police Chief John Incontro, a former LAPD SWAT captain.
“Even if you see the muzzle flash, we are talking officers with pistols,” Incontro said. “Even with rifles, you have a prospect of missing and harming others.”
Experts believe the Las Vegas massacre will force a shift in the paradigm for policing outdoor events. Locations will be vetted for quick escape routes for large crowds. Event organizers might be asked to have materials on hand that could become a makeshift fence. Tactical plans could be drawn up for areas such as L.A. Live where skyscrapers loom.
Los Angeles police currently station counter-snipers at open-air events, but the tactic is used sparingly and only for major affairs, such as award shows. A counter-sniper would have to be positioned higher than the shooter.
After a five-hour standoff with a gunman in Sunland, Los Angeles police were ordered to fire from a helicopter. The man was at the top of the hill in a house and had been difficult for responding officers to reach. Chief Charlie Beck said the decision to employ the tactics was made at the highest levels of the department.
It’s not clear if that approach would have been effective in a situation like Las Vegas.
“You have to get pretty close for that shot,” said Incontro, adding that a sniper could also be compelled to shoot at the helicopter, possibly forcing it into the ground.
Paddock’s plan of attack was similar to that of Charles Whitman, a former Marine sharpshooter who opened fire from a tower at the University of Texas at Austin in 1966.
Whitman, who lost his scholarship to the school a few years earlier, had taken an elevator to the 27th floor, where he hauled rifles up two flights of stairs to the observation deck. Sixteen people were killed.
Paddock was at an even higher distance and armed with weapons modified to rapidly fire when he began his relentless attack on the crowd below.
He was able to create a setting similar to that of a battlefield, said James Allen Fox, a Northeastern University criminologist who researches mass killings.
Those watching country singer Jason Aldean perform Sunday night dismissed the initial gunshots as firecrackers.
Then bodies began to drop.
“We’ve got to go!” Jared Birnbaum heard his girlfriend say before she disappeared in the chaos.
He scrambled to an exit only to be stopped by a police officer redirecting the mob. Birnbaum then dove under nearby bleachers, joining hundreds of others.
By then, the 30-year-old was covered in blood — most of it from other people — and hearing talk of multiple shooters. He feared being taken hostage in what felt like a fishbowl of raining bullets.
“All you could do is duck and put your hands behind your head,” he said, “and hope you’re not one of the ones to go.”
Times staff writer Kate Mather contributed to this report from Las Vegas.