Police say three people have been killed in a shooting at the Las Vegas campus of the University of Nevada (UNLV) on Wednesday morning.

Officers said the suspect, who remains unnamed, was found dead at the scene.

One other victim remains in a critical condition at a local hospital, police said in a statement.

UNLV and all other southern Nevada System of Higher Education institutions across the state will be closed for the rest of Wednesday.

The university first tweeted at around 11:53 local time (19:53 GMT) that police were responding to reports of shots fired on campus.

About 20 minutes later, the university said campus police were responding to an additional report of shots near the Student Union building.

It warned students at Beam Hall to "evacuate to a safe area" and to "RUN-HIDE-FIGHT", which is a common active shooter protocol in the US.

Law enforcement said they immediately responded and engaged the suspect, who is now dead.

Kevin McMahill, Las Vegas Metropolitan Police Department sheriff, said at a press conference that they have "no idea on the motive" as of now.

"There are a number of victims that have been transported to area hospitals," he told reporters.

Shortly after the press conference ended, the sheriff said on X, formerly known as Twitter, that "there are three victims", but the extent of their injuries are unknown.

But on Wednesday evening police said in a statement that the victims had died from their injuries.

"One additional victim in critical condition at a local hospital," the statement added.

One student who was on campus told a local ABC station that it seemed like police were on campus right away.

Describing the scene to the reporter he said: "You don't know what to do. You're calling your family, texting your friends like 'I love you guys' because he [the shooter] could burst through the door at any minute."

A ground stop was issued at Las Vegas' Harry Reid International Airport, with authorities citing security reasons. The airport is near the site of the reported shooting.

White House spokesperson Karine Jean-Pierre said the White House was monitoring the situation.

Carolyn Goodman, mayor of Las Vegas, called it "tragic and heart-breaking news" and said she was "praying for everyone on campus".

Shortly before 13:00 local time, the university said police were "evacuating buildings one at a time".

Nevada's Governor Joe Lombardo said his office was in "constant communication" with Las Vegas police, the university and emergency responders.

The Federal Bureau of Investigation (FBI) and The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) are assisting local police with the investigation.

The Clark County Fire Department has established a family reunification centre at the Las Vegas Convention Center,