Alongside First Lady Melania, the President met some of the heroic police officers who had tracked gunman Stephen Paddock to the 32nd floor of the Mandalay Bay hotel.
The couple also met Clark County Sheriff Joseph Lombardo, before visiting survivors and their family members at a hospital.
Yesterday’s trip was the first time in his presidency that he has had to deal with the aftermath of a major mass shooting of the type that has become all too familiar.
Mr Trump said last night: “It’s a very, very sad day for me, personally. We are going to pay our respects and to see the police who have really done a fantastic job in a very short time.”
The President added that investigators were “learning a lot more” about the gunman and that those details would be announced at “an appropriate time”.
Mr Trump previously denounced 64-year-old Paddock as a “sick, demented man” and vowed to look at him “very seriously”.
After arriving on Air Force One yesterday, Mr Trump’s motorcade passed both the Mandalay Bay hotel and the site of the Route 91 country music festival.
He was also expected to meet Nevada’s governor, Brian Sandoval, and the city’s mayor, Carolyn Goodman.
The President had held a moment of silence on the White House south lawn and ordered flags lowered to half-mast.
In an address to the nation, he said the US was joined in “sadness, shock and grief”.
Mr Trump, also tweeted his “warmest condolences” to the victims of the shooting.
He added: “This was an act of pure evil. I want to thank the Las Vegas Metropolitan Police Department and all of the first responders for their courageous efforts. The speed with which they acted is miraculous and prevented further loss of life.
“I know we are searching for some kind of meaning in the chaos, some kind of light in the darkness. The answers do not come easy.”
The shooting has reignited a debate in the US about whether more gun control legislation might have prevented the slaughter.
Republicans who control the US Congress have shown little inclination to respond to Democratic calls for extra gun measures.
Mr Trump, a Republican who broadly supports the gun lobby, was asked on Tuesday whether it was time to debate gun control measures.
He said: “Perhaps that will come. But that’s not for now.”