President Donald Trump told first responders that they should be proud of the way they responded to the mass shooting Sunday night in Las Vegas.

At Las Vegas Metropolitan Police Headquarters, Trump said, "You showed the world and the world is watching." Trump and his wife, Melania, were meeting with victims, doctors, police, dispatchers and others who responded to the tragedy, when a gunman in a hotel tower opened fire on an outdoor country music festival. Fifty-nine people were killed and more than 500 injured - some from being shot and others from the chaotic escape.

Earlier, Trump said the meetings and the response made him "proud to be an American."

Trump also said he met "some of the most amazing people" during his visit to a hospital where victims are being treated.

And he said he's invited some of those survivors to the White House.

He says he wants to "congratulate everybody" at the hospital and says it's "incredible" what doctors have done.

He adds: "It makes you very proud to be an American when you see the job that they've done."

Trump was speaking in the lobby of the University Medical Center.

Speaking to reporters on Tuesday, Trump said he’d be in Las Vegas to “pay our personal respects and condolences to everybody. What happened is such a tragedy. So unnecessary. Who can believe what happened to Las Vegas?” He later added that it was “a very horrible thing even to think about.”

As the president departed the White House, he told reporters, "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." He also said officials were learning "a lot more" about the shooter, Stephen Paddock, and that information about him would be released "at an appropriate time." "It's a very, very sad day for me, personally," the president said.  

Trump’s trip to Las Vegas follows his Tuesday travel to hurricane-ravaged Puerto Rico. During that 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 focused on the best of the reviews he and his administration are getting rather than criticism of the federal response to Hurricane Maria.

As he left for Puerto Rico, Trump called the Las Vegas gunman “demented” and a “very, very sick individual.” Trump also praised Las Vegas police, saying they had done an “incredible job.”

Asked about gun laws, the president said “we’ll be talking about gun laws as time goes by.”

The rampage by Stephen Craig Paddock killed at least 59 people and injured 527, some from gunfire and some from a chaotic escape.

Trump offered somber remarks about the shooting from the White House on Monday, saying “our unity cannot be shattered by evil, our bonds cannot be broken by violence.”

(The Associated Press, CBS News contributed to this report.)