Police responded to a shooting on the city’s east side soon after 5:30 pm local time (0130 GMT Saturday), Lieutenant Jason Johansson told a news conference carried by KSNV News 3, Las Vegas.
At least one victim died in hospital, Johansson said, but local media later reported that two homeless people were killed and three wounded.
“I wish I could say that I knew for a fact that it was an isolated (incident),” he said. “Right now I’m treating it as ‘I don’t know’.”
The shooting comes less than a week after three homeless people were killed in separate but similar incidents in Los Angeles.
All three victims were killed as they slept alone outside and Los Angeles police said they are pursuing a lone suspect.
Asked if the Las Vegas incident could be related to the Los Angeles shootings, Johansson said “this is quite a bit different… so I’m not inclined to say that it is related.”
“But if our investigation takes us that route then we’ll go there, but we’re not there right now,” he said.
Mass shootings are alarmingly common in the United States, where there are more guns than people and where attempts to clamp down on their spread are always met with stiff resistance.
The United States has recorded more than 500 mass shootings this year, according to the Gun Violence Archive, a non-governmental organization that defines a mass shooting as four or more people wounded or killed.