- Video report by Washington Correspondent Robert Moore
Police are still seeking to explain what drove 64-year-old gunman Stephen Paddock to open fire on a crowd at an open air concert in Las Vegas - the deadliest US shooting in modern history.
US President Donald Trump has branded Paddock "sick" and "demented" a day after describing the attack that killed 58 people and injured 527 as an "act of pure evil".
They were shot while fleeing the Route 91 Harvest Festival on the Las Vegas Strip as Paddock opened fire from a skyline room at the nearby Mandalay Bay Resort and Casino on Sunday at 10pm local time.
A GoFundMe page set up to help provide relief and support to the victims and their families has received more than £2 million in donations.
Investigators discover Paddock's arsenal of weapons
Las Vegas Metropolitan Police Department (LVMPD) said Paddock was found dead by SWAT officers on the hotel's 32nd floor, more than an hour after the initial call to police reporting gunfire.
Assistant Sheriff Todd Fasulo later said 23 guns were found in Paddock's hotel room.
A further 19 guns were found during a raid on Paddock's home in the the city of Mesquite, around 80 miles north-east of Las Vegas.
A separate raid was also taking place on another property owned by the gunman in Reno, Nevada.
Mr Fasulo said the investigation into the mass shooting was a homicide investigation and that the gunman's motives remained unclear.
LVMPD said Paddock had been staying at the hotel since September 28.
President Trump responds to gun control calls
Responding to calls for enhanced gun controls in the wake of the latest mass killing, the pro-gun President Trump told reporters "we'll be talking about gun laws as time goes by".
He made the brief statement before flying down to Puerto Rico. He is due to visit Las Vegas on Wednesday as the investigation continues into Paddock.
On the gunman, Mr Trump said: "Lot of problems, I guess, and we're looking into him very, very seriously."
In a statement on Monday, Mr Trump said the United States was "joined together in sadness, shock and grief".
The president said he and First Lady Melania Trump were praying for everyone affected by the shooting.
"We cannot fathom their pain, we cannot imagine their loss," he said.
"To the families of the victims, we are praying for you and we are here for you and we ask God to help see you through this very dark period."
He added: "In moments of tragedy and horror, America comes together as one."
He said they had helped save many lives by finding the gunman so quickly.
A minute's silence was held at the White House in memory of those killed in the shooting.
Video captures moment gunman opened fire
Video footage shared on social media showed people sprinting in panic as bullets rained from above during a performance by country singer Jason Aldean in front of a crowd of 22,000.
Aldean was in the middle of a song when the shooting began. Video of the incident then showed Aldean stopping his performance and the crowd becoming quiet.
The gunman then fired another volley, the muzzle flashes visible from the casino, as more victims fell to the ground, while others fled in panic. People used parked cars and snack bars to take cover.
Witnesses described hearing hundreds of rounds being fired from above, with some people believing an automatic weapon had been used.
Witness Jon Bessette, who had been at the concert, told NBC News: "The band ran off stage and it was pandemonium. Everyone was running, people were getting trampled."
Another witness said they heard a "pop, pop, pop" sound, similar to fireworks, as they watched the show.
Confusion in aftermath of the attack
Officers had announced they were hunting a 62-year-old woman, Marilou Danley, who they believed had been "travelling" with the suspect.
She was later located abroad and is now not believed to have been involved in the attack.
So-called Islamic State then claimed responsibility for the attack, saying the shooter converted to Islam months ago, but provided no evidence to support the claim.
The FBI said there is no connection between Paddock and an international terror group.
Britain reacts to 'appalling attack' as May backs call for gun control
Prime Minister Theresa May has told ITV's Good Morning Britain the attack highlights the difference between US and UK gun laws.
"Obviously it's a direct contrast with this country where we have very tough gun laws," she said, referring to Paddock's arsenal of weapons.
"Most people would look at this and assume that people in America would be so shocked at this attack that they would want to take some action," Mrs May said.
She and Foreign Secretary Boris Johnson both condemned the attack as the scale of the death toll continued to rise on Monday.
The Queen and Prince Philip also sent a message of condolence to President Trump, saying they are "saddened to learn of the terrible attack in Las Vegas".
"Our thoughts and prayers are with the victims and their families and those who have been injured," they said.
Are there fears of a continued threat?
The US Homeland Security Department later said there was no "specific credible threat" involving other public venues in America.
Police shut down the usually busy Las Vegas Boulevard and authorities across the state and federal ranks converged on the scene as dozens of ambulances ferried those struck by gunfire.
Nearby Interstate 15 and flights at McCarran International Airport were briefly closed.
In a press conference, Sheriff Lombardo said he was "pretty confident" there was no longer a wider threat in Las Vegas, describing the suspect as the "sole aggressor".
Sheriff Lombardo also said a number of police officers, both on and off duty, were among those killed and hurt.