It took about 10 minutes for Stephen Paddock to carry out the deadliest mass shooting in modern US history.
From his position at a Las Vegas hotel, Paddock fired a barrage of bullets at 22,000 concertgoers below at a country music festival -- made possible through what appeared to be meticulous planning.
The shooter had checked into a hotel room overlooking the music festival, stocked a cache of weapons there and set up cameras inside his hotel suite and hallway.
The first call of shots being fired came Sunday, 10:08 p.m. and the gunfire stopped at 10:19 p.m., said Clark County Undersheriff Kevin McMahill on Tuesday. He said the shooting went off and on for nine to 11 minutes.
The massacre left 58 people dead and another 500 people wounded from gunshots to stampede injuries.
No one knows why Paddock gunned them down.
But authorities are hoping for clues as his girlfriend, Marilou Danley returned to the United States Tuesday night from the Philippines. She is being accompanied by the FBI in Los Angeles, where Las Vegas police plan to question her, a law enforcement source told CNN.
Police believe Paddock acted alone.
He had an arsenal of weapons, including bump-fire stocks found in the hotel, which is a legal device that enables a shooter to fire bullets rapidly, similar to an automatic rifle. Paddock had outfitted 12 of his firearms with the bump stocks, according to the Bureau of Alcohol, Tobacco, Firearms and Explosives.
The shooter also had cameras set up inside and outside the suite. Police are not aware whether the devices were transmitting -- the FBI is investigating their use -- but the Clark County sheriff told reporters he thinks Paddock might have used them to watch for people approaching his room. One camera looked out the peephole on the suite's door.
The hail of gunfire stopped when security guards approached Paddock's Mandalay Bay hotel room, McMahill said. Paddock turned his attention to those outside his door and fired, wounding a security guard who was advancing towards his room.
The security guard was "very heroic" and provided police with information about the shooter's location, McMahill said. When officers entered the hotel room, they found Paddock dead. Authorities believe he killed himself.
-- Paddock's girlfriend, Danley flew to LAX from Manila, said Maria Antoinette Mangrobang, a spokeswoman for the Bureau of Immigration in the Philippines. Paddock lived in Mesquite, Nevada, with Danley, who was out of the country during the shooting, police said. She had entered the Philippines in September 15, and again on September 25, traveling on her Australian passport, she said. There has been communication between authorities in the Philippines, the FBI and US Department of Homeland Security, Mangrobang said.
-- Paddock wired $100,000 to the Philippines, a law enforcement source said. However, officials haven't able to see yet precisely when the wire happened or who was the recipient. The FBI is working with Filipino authorities to determine details.
-- More than three dozen of the 58 people killed have been publicly identified. Among the latest: Charleston Hartfield of Nevada; Stacee Etcheber of California; Christopher Roybal of Colorado; Hannah Ahlers of California; and Jordan McIldoon of British Columbia, Canada.
-- Clark County Coroner John Fudenberg said 58 people were killed. Authorities had previously said 59 were killed in the shooting, but on Tuesday clarified that number included the shooter.
-- The Daily Mail newspaper of the UK published several photos taken in Paddock's room after the shooting. In one photo, the legs of a dead shooter can be seen on the floor. The photos show semiautomatic assault-style rifles on the floor and on furniture. Stacks of ammunition magazines used in rifles can also be seen. Police said they're investigating the source of the leak.
-- A total of 47 guns have been recovered from three locations: Paddock's hotel room and his two Nevada homes in Verdi and Mesquite. The guns were bought in Nevada, Utah, California and Texas, said Jill Snyder, special agent in charge of ATF field division in San Francisco. Thousands of rounds of ammunition were found in his Mesquite home and an ingredient used in explosives was discovered inside the shooter's car.
-- Police released the first body camera footage in the shooting.
'I felt him get shot in the back'
The massacre started during the Route 91 Harvest festival as the rapid staccato of gunfire confused, then alarmed concertgoers. They scrambled to flee the gunman's aim.
Heather Melton heard the noise interrupting the concert and told her husband, Sonny, she thought it might be gunfire. He, like most people, thought it was fireworks.
Then the bullets started ricocheting off the ground around the Tennessee couple. She wanted to get low; he said, no, we'll get trampled.
So they ran away from the gunfire, Sonny just behind Heather, until he was felled by a bullet.
"I felt him get shot in the back," she told "Anderson Cooper 360." There were bodies all over the ground.
"I was trying to talk to him and he wasn't responding," said Heather, an orthopedic surgeon. She said she got over him and started doing CPR. Sonny, a registered nurse, was bleeding from the mouth.
Heather Melton said she knew he probably was gone, but she wanted to hope.
Sonny was declared dead at the hospital.
"He was the most selfless person that I ever met, and even until his last breath he proved that," Heather said.
Questions about Paddock
The mass shooting has raised questions about the gunman, his intentions and his access to weapons.
Paddock's violent transformation has mystified everyone -- his brother, investigators and the families he victimized. The 64-year-old, retired, twice-divorced accountant had no significant criminal history and was previously unknown to police.
The massacre has no known link to overseas terrorism or terror groups, a US official with knowledge of the case said. And authorities say it's too early to tell whether the killings were an act of domestic terrorism.
"We have to establish what his motivation was first," Clark County Sheriff Joe Lombardo said.
For an act to be considered terrorism, it must appear that it was intended to intimidate or coerce a civilian population, or try to influence political change.
President Donald Trump on Tuesday didn't say whether he thought the shooting was an act of domestic terrorism.
When asked whether he was open to a discussion on gun control, Trump said, "At some point perhaps that will come. That's not today."