President Donald Trump has met victims of the Las Vegas shooting in hospital and praised doctors for doing an "indescribable" job in treating them.
Speaking to reporters from the lobby of the University Medical Center, Mr Trump said he and first lady Melania had met "some of the most amazing people" and invited those injured to visit him at the White House.
He also commended the doctors who had worked to save victims for doing an "indescribable" job.
"It makes you very proud to be an American when you see the job that they've done," he said.
Mr Trump then headed to the Las Vegas Metropolitan Police headquarters, where he met police officers and dispatchers who had responded to the shooting. He congratulated them "on a job well done".
"You showed the world and the world is watching," he told them. "And you showed what professionalism is all about."
Air Force One landed at the airport near the famed Las Vegas strip on a bright, sunny morning just days after a gunman on the 32nd floor of a hotel and casino opened fire on people at an outdoor country music festival below.
The Sunday night rampage killed at least 59 people and injured 527, some from gunfire and some from a chaotic escape.
President Trump in Las Vegas:
“The souls of those who passed are now at peace in Heaven.”pic.twitter.com/Dr1ld6pDNa— GRANT J. KIDNEY 🇺🇸 (@GrantJKidney) October 4, 2017
"It's a very sad thing. We are going to pay our respects and to see the police who have done really a fantastic job in a very short time," Mr Trump told reporters before departing the White House.
He said that authorities were "learning a lot more" about gunman Stephen Paddock, and that more details would be "announced at an appropriate time".
"It's a very, very sad day for me personally," he said.
On his trip from the airport, the president's motorcade drove past the Mandalay Bay hotel where the gunman fired down into the concert crowd.
Air Force One departs Las Vegas past the broken windows on the Mandalay Bay hotel. (Photo: Mike Blake/Reuters) pic.twitter.com/iVFjAOjD6d— Colin Campbell (@colincampbell) October 4, 2017
Mr Trump's trip to Las Vegas follows his Tuesday visit to hurricane-ravaged Puerto Rico - a pair of back-to-back episodes that are testing his ability to unite and lift the nation in times of strife.
Mr Trump, a leader who excels at political provocation and prides himself on commanding strength, has sometimes struggled to project empathy.
During Tuesday's trip, he highlighted Puerto Rico's relatively low death toll compared with "a real catastrophe like Katrina", when as many as 1,800 people died in 2005 as levees protecting New Orleans broke.
He also pointed repeatedly to praise his administration had received for its efforts, despite criticism on the island of a sluggish response.