The death toll from the mass shooting at a Las Vegas country music concert has risen to at least 58, with more than 515 people listed as wounded, police said on Monday.
Paddock killed himself as special response team officers broke into the hotel room, police said.
President Donald Trump discussed the massacre during a brief address delivered at the White House, saying "it was an act of pure evil."
Trump said he planned to travel to Las Vegas on Wednesday to meet with law enforcement personnel, other first responders and relatives of the victims.
"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," Trump said. "Scripture teaches us the Lord is close to the broken hearted and saves those who are crushed in spirit. We seek comfort in those words for we know that God lives in the hearts of those who grieve."
Paddock opened fire around 10.08 p.m. as about 22,000 people were attending the final concert in the Route 91 Harvest, a country music festival.
Singer Jason Aldean was on stage when the shooting started and can be seen on videos running for cover.
Police have not revealed a motive for the massacre, the deadliest mass shooting in US history.
The gunman's roommate, Marilou Danley, was initially identified by police as a person of interest in the case, but authorities later said they did not believe she was involved in the shooting.
Paddock's brother, Eric, told US media outlets at his home in central Florida that the shooting came as a complete surprise to him.
"I don't understand. It doesn't make sense," Eric Paddock told Orlando's WFTV Channel 9.
Stephen Paddock lived in Melbourne, a city on Florida's east-central Space Coast, until 2015, officials said.
"There's nothing I can say. My brother did this. It's like he shot us. I couldn't be more dumbfounded," Eric Paddock said.
Eric Paddock said he had not heard from his brother since last month, when Stephen texted him to see how the family had fared with Hurricane Irma.
He told the Orlando Sentinel that his and Stephen's father was Benjamin Hoskins Paddock, a career criminal and convicted bank robber.
The FBI, meanwhile, said it could not find any links between Paddock and foreign terrorist organisations.
"We have determined, to this point, no connection with an international terrorist group," an FBI spokesman said in a press conference in Las Vegas. "As this investigation continues, we will continue to work with our partners to ensure that this is factually, thoroughly and absolutely investigated, to be able to bring comfort and peace back to this community."
The Islamic State terror group claimed responsibility Monday for the mass shooting in Las Vegas.
The IS said in a statement, whose authenticity has not been verified, that the gunman was "a soldier of the Islamic State".
The terrorist group has falsely claimed responsibility in the past for attacks.
Investigators are still trying to identify all the victims of the mass shooting, Las Vegas Metropolitan Police Department (LVMPD) Sheriff Joe Lombardo said in a press conference.