Washington: US President Donald Trump said the quick response of law enforcement during the deadliest mass shooting in modern American history was "in many ways, a miracle".

"Look, we have a tragedy. What happened is, in many ways, a miracle," Trump said as he departed the White House for a trip to Puerto Rico on Tuesday morning local time.

"The police department, they've done such an incredible job. And we'll be talking about gun laws as time goes on. But I do have to say, how quickly the police department was able to get in was really very much of a miracle. They've done an amazing job."

At least 58 people were killed and more than 500 others were injured in Las Vegas late on Sunday when Stephen Paddock, a 64-year-old retiree who lives in the area, opened fire on an outdoor country music festival from the windows of a 32nd-floor hotel suite. For nine minutes , bullets rained down on the concertgoers and the panicked crowd rushed to escape. As Paddock fired round after round, gun smoke filled the hotel suite and set off a fire alarm, allowing a SWAT team to zero in on Paddock's position in about 20 minutes. As officers closed in, Paddock killed himself.