Las Vegas resident Stephen Paddock, 64, has been identified as the man who killed more than 50 people and injured 200 others attending an outdoor concert.

It is being identified as the deadliest mass shooting attack in modern US history.

The lone gunman opened fire at the open-air Route 91 festival, unloading hundreds of rounds of ammunition from a room high up at the Mandalay Bay casino complex.

Witnesses say the shots appeared to come from a balcony on the adjoining casino, aimed at the crowd of 40,000 people on the ground below.

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SUSPECTS IDENTIFIED

Las Vegas Sheriff Joe Lombardo has confirmed the suspect, described as a "local", has been killed and stated they believed there were no more active shooters.

The gunman has been identified as 64-year-old Stephen Paddock, a Las Vegas resident living in a local retirement community.

A property linked to him has been raided.

Marilou Danley and the car police were interested in identifying. Photos / Supplied
Marilou Danley and the car police were interested in identifying. Photos / Supplied

A local reporter named Lucas Thomas said on Twitter: "PIO Quinn Averett for Mesquite police tells me they had no prior run-ins with alleged shooter.

"Paddock lived in a retirement community in #Mesquite called "Sun City". Averett confirms [his companion, who police said they were looking for after the shooting] Marilou Danley lived with Paddock.

"Danley, like Paddock, never had any run ins with police in #Mesquite," Averett said.

"Too early to speculate as to motives.

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"Averett said investigation will take a long time. Scene to be opened after warrant executed."

Sheriff Lombardo said numerous firearms had been located within the room that Paddock occupied in the casino. He opened fire from the 32nd floor of the Mandalay Bay casino.

Police used explosives to blast their way into the room where he was "engaged".

Police say they believe they have located the gunman's "partner", earlier identified as a "person of interest". She has been named by police as Marilou Danley.

A wounded woman is moved outside the Tropicana during an active shooter situation on the Las Vegas Strip. Photo / AP
A wounded woman is moved outside the Tropicana during an active shooter situation on the Las Vegas Strip. Photo / AP

Marilou Danley is described as an "Asian female" and is about 150cm tall and weighs 50 kilograms.

The two cars police had been seeking, a Hyundai Tuscon NV plate 114 B40 and a Chrysler Pacifica Touring NV plate 19D 401, have also been found.

Fighting back his emotions in a press conference, Clark County Sheriff Joseph Lombardo said the woman and the cars had been found and police were now searching the home and hotel room where the shooter stayed.

"We have located the vehicles in question, and we are confident we have located the female person of interest," he said.

"We have officers at his residence and we'll be executing a search warrant there shortly," he said, adding that the horror had taken a huge toll on the force.

"We're holding up. we're doing the best we can," he said.

"We're going to have to look out for their well-being moving forward," he said about first responders on the scene.

Danley is believed to be a "gambling and casino professional" who lived in Reno, Nevada. She is thought to have been a former housemate of the suspected shooter.

She worked as a hostess for Atlantis Casino between 2010 and 2013 according to her LinkedIn profile.

Sheriff Lombardo said two police officers who were off duty are among those who have died. Another on-duty officer is in a critical condition, while another was wounded in the deadly shooting.

Police have appealed for anyone with information, including mobile phone footage to come forward.