At least 58 people are dead and more than 500 injured after the deadliest mass shooting in US history struck a country music festival in Las Vegas on Sunday night.

Automatic gunfire rained down on concertgoers from the 32nd floor of the Mandalay Bay hotel, just over the main Las Vegas Boulevard from the scene, police said. 

The attacker, who police identified as a white 64-year-old man named Stephen Paddock, shot himself before police entered the hotel room where he fired from. His motive is not yet known and officials initally held back from describing the incident has 'domestic terrorism'. 

The Department for Homeland Security said there was no 'specific credible threat involving other public venues'.

'We have no idea what his belief system was,' said Joseph Lombardo, the sheriff of the Las Vegas Metropolitan police department. He later added: 'We have to establish what his motivation is first. There is motiving factors associated with terrorism other than a distraught person just intending to cause mass casualty. Before we label with that [terrorism] it will be a matter of process.'

Police found at least 10 guns in his hotel room where he had been staying since September 28. 

The death toll has surpassed the Orlando shooting at the Pulse nightclub in June 2016 where 49 people were killed, and is expected to rise further. 

Speaking from the White House Trump quoted the Bible as he spoke extensively about faith and prayer in his response, condemning the attack as an 'act of pure evil'. 

He said: 'To the families of the victims; we are praying for you, we are here for you, and we ask God to help see you through this very dark period.'

Quoting Psalm 34 he went on: 'Scripture teaches us "the Lord is close to the broken hearted and saves those who are crushed in spirit".

'We seek comfort in those words for we know God lives in the hearts of those who grieve.'

He praised the Las Vegas police and said they showed what 'true professionalism' looked like, highlighting the speed at which they identified the attacker's location. 

Paddock's accomplice, Marilou Danley, has been detained. Authorities were earlier seeking an Asian female described as a companion of the suspect.

Witnesses described seeing flashes of light from the upper floors of the hotel during a performance by country music star Jason Aldean who later posted on social media calling on people to pray.

Writing on Instagram he said: 'Tonight has been beyond horrific. I still don't know what to say but wanted to let everyone know that Me and my Crew are safe. 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.'

Hundreds of people fled the scene and videos posted on social media showed an extended period of gunfire.

The three day music festival began on Friday and has been held for the past four years on an 15-acre lot across Las Vegas Boulevard from Mandalay Bay.