People scramble for shelter at the Route 91 Harvest country music festival after apparent gun fire was heard on October 1, 2017 in Las Vegas, Nevada. (Photo: AFP)

Las Vegas: The Islamic State group has claimed responsibility for the mass shooting in Las Vegas, saying that the perpetrator was "a soldier" who had converted to Islam months ago, without providing any evidence to support the claim.

The group released two statements on its Aamaq news agency on Monday, hours after the shooting at a country music concert that killed at least 58 people and wounded at least 515.

It did not name the suspected shooter, identified by Las Vegas police as 64-year-old Stephen Paddock, but said he had "executed the operation in response to calls to target countries of the coalition" batting the extremist group in Iraq and Syria.

IS often claims attacks by individuals inspired by its message but with no known links to the group.

A gunman opened fire on fans at a US country music concert on the Las Vegas Strip, police said.

The gunman, who police said was a local resident identified as Stephen Paddock, 64, was killed after being "engaged" by officers who responded to report of gunfire from the 32nd floor of the Mandalay Bay, a hotel-casino next to the concert venue.

"We believe the individual killed himself prior to our entry," Las Vegas Sheriff Joseph Lombardo told media.

He said officers found "in excess of 10 rifles" upon entering the 32nd floor hotel room from which a gunman opened fire at concertgoers below, killing at least 50 and injuring hundreds.

Revellers screamed and fled in panic as a steady stream of automatic gunfire rang out at the venue shortly after 10:00 pm local time, footage captured on smart phones showed.

 

"We have in excess of 200-plus injured and excess of 50-plus that have died at this point," Las Vegas Metro Police Sheriff Joseph Lombardo told an early morning press conference. Two of those killed are believed to be off-duty police officers, said Lombardo.

"This is an ongoing investigation, but we are comfortable that the primary aggressor in this event is -- has expired or passed away, and is no longer a threat."

The sheriff said they believe this was a "lone wolf" attack but said they are looking for a roommate of the dead suspect as a person of interest.

Thousands of fans were attending the concert next to the Mandalay Bay which was part of a three-day country music festival known as Route 91.

- 'Like firecrackers' -

Witnesses told how the gunman opened fire with an initial burst and then appeared to reload as he continued his spree.

"We heard (what) sounded like a glass breaking, so you looked around to see what's going on and then heard a pop, pop, pop," Monique Dekerf told CNN.

"You'd think for a moment okay we're fine, there's no more gunfire, then it starts again."

Her sister Rachel said it sounded like "the shots were coming from the right side ... it sounded like they were right beside us too ... it was right there."

Best-selling country singer Jason Aldean was on stage at the time of the shooting which came towards the end of the concert.

"We were watching the concert having a great time, and then we heard what sounded like firecrackers," witness Joe Pitz told the local Las Vegas Sun news outlet.

"I guess it was an automatic weapon going off but it literally sounded like firecrackers.

"Then soon enough there was commotion on the Mandalay Bay side of the stage. They were motioning for medics to come and safety people to come and Jason Aldean ran off the stage.

"Everybody in the vicinity went down. I don't know if they were ducking or if they were but it was chaos."

- 'Beyond horrific' -

It was the deadliest shooting in the United States since 49 people were killed at the Pulse nightclub in Orlando, Florida in June 2016. It was also the latest in a series of recent deadly attacks at concert venues.

Twenty-two people were killed while leaving a concert in the northern English city of Manchester in May when a suicide bomber detonated a nail bomb in the foyer.

Ninety people were killed in November 2015 at the Bataclan venue in Paris during a concert by the US band the Eagles of Death Metal.

Lombardo would not release the name of the gunman, but said he was a local man and issued an appeal for information about his companion.

The sheriff however, believing it as 'lone wolf", attack issued an appeal for information about his female traveling companion, identified as Marilou Danley.

"We have not located her at this time and we are interested in talking to her for follow-up," Lombardo said.

"We are pretty confident there is no longer a threat other than we are attempting to locate the person of interest.

"It's on ongoing investigation. Right now, we believe he is the sole aggressor at this point."

A shocked Aldean told his fans via Instagram that he and his band was safe. "Tonight has been beyond horrific," the singer wrote. "I still dont know what to say ... My Thoughts and prayers go out to everyone involved tonight.

"It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night."