LAS VEGAS — The victims just kept coming.
In cars, in ambulances waiting four or five deep, from the walking wounded to the barely alive, they arrived in droves.
"I have no idea who I operated on," said Dr. Jay Coates, a trauma surgeon whose hospital took in many of the wounded after a gunman opened fire from his 32nd-floor hotel suite Sunday night on a country music concert below. "They were coming in so fast, we were taking care of bodies. We were just trying to keep people from dying."
It was the deadliest mass shooting in modern U.S. history, with at least 59 killed and 527 injured, some by gunfire, some during the chaotic escape. Scores remained in critical condition Tuesday.
University Medical Center of Southern Nevada was one of many hospitals that were overflowing.
"Every bed was full," Coates said. "We had people in the hallways, people outside and more people coming in."
He said the huge, horrifying wounds on his operating table told him this shooting was something different.
"It was very clear that the first patient I took back and operated on that this was a high-powered weapon," Coates said. "This wasn't a normal street weapon. This was something that did a lot of damage when it entered the body cavity."
The gunman, 64-year-old high-stakes gambler and retired accountant Stephen Paddock, killed himself as authorities stormed his hotel room at the Mandalay Bay hotel casino.
He had 23 guns — some with scopes — in the room where he had been staying since Thursday. He knocked out two windows to create sniper's perches he used to rain rapid fire down on the crowd of 22,000 people some 500 yards away.
He also had two "bump stocks" that can be used to modify weapons to fire continuously, as if fully automatic, according to two U.S. officials briefed by law enforcement who spoke on condition of anonymity because the investigation is still unfolding.
At Paddock's home, authorities found 19 more guns, explosives and thousands of rounds of ammunition. Also, several pounds of ammonium nitrate, a fertilizer that can be turned into explosives, were in his car, authorities said.
The FBI discounted the possibility of international terrorism, even after the Islamic State claimed responsibility for the attack. But beyond that, the motive remained a mystery, with Sheriff Joseph Lombardo saying: "I can't get into the mind of a psychopath at this point."
While Paddock appeared to have no criminal history, his father was a bank robber who was on the FBI's most-wanted list in the 1960s.
"I can't even make something up," his brother in Florida, Eric Paddock, said when asked what might have motivated his brother. "There's just nothing."
President Donald Trump on Tuesday called the gunman "demented" and a "very, very sick individual." Asked about gun laws, the president said, "We'll be talking about gun laws as time goes on."
His muzzle flashes visible in the dark, Paddock began shooting just after 10 p.m. and appeared to fire unhindered for more than 10 minutes, according to radio traffic, as police frantically tried to locate him.
"We can't worry about the victims," an officer said over the radio at 10:15 p.m. "We need to stop the shooter before we have more victims. Anybody have eyes on him ... stop the shooter."
The crowd, funneled tightly into a wide-open space, had little cover and no easy way to escape. Victims fell to the ground, while others fled in panic. Some hid behind concession stands or crawled under parked cars.
See all coverage of the Las Vegas shooting here.