Police confirm that the suspect is now dead.
At least 50 people have been killed and more than 400 injured in the deadliest mass shooting in US history, after automatic gunfire was heard at a country music festival in Las Vegas, Nevada.
The shooting took place near the Mandalay Bay Hotel at around 22:30pm local time (05:30am GMT) when a gunman is reported to have opened fire at the Route 91 event being held on the Las Vegas strip.
Videos on social media from the concert show hundreds of people fleeing the scene, and the sound of what appears to be prolonged automatic gunfire can be heard as singer Jason Aldean performed.
Las Vegas police have now confirmed that at least 50 people are dead, including two off-duty police officers, and over 400 injured.
Sheriff Joseph Lombardo revealed that a suspect believed to be the "primary aggressor" in the incident is also dead, while officers are "pretty confident" there is no longer a threat.
The suspect has now been named by police as 64-year-old Stephen Paddock, said to be local to Las Vegas.
Police had earlier named a 62-year-old woman, Marilou Danley, as a person of interest to their investigation.
A later update from police confirmed that Danley had been found, was unharmed and had in fact been out of the country at the time of the shooting.
"She was not with him when he checked in, we have discovered. He was utilising some of her identification," said Sheriff Lombardo.
"We have had conversation with her and we believe her, at this time, not to be involved."
There are reports that the shooting came from the 32nd floor of the Mandalay Bay hotel, with people reporting seeing flashes from the upper floors.
The Mandalay Bay Resort has since issued a statement, adding: "Our thoughts & prayers are with the victims of last night's tragic events. We're grateful for the immediate actions of our first responders."
Las Vegas Metropolitan Police Department's Twitter account originally said: "Confirming that one suspect is down. This is an active investigation. Again, please do not head down to the Strip at this time.
"At this time we do not believe there are any more shooters. More information to come shortly from @Sheriff_LVMPD."
The police also added: "Please do not livestream or share tactical positions of our officers on scene. This may put emergency responders in danger."
An eyewitness told Fox News: "It was bad. There were multiple people hit, a lot of people shot. The area we had for medics was completely flooded with people.
"We carried at least four or five people to the MT area.
"Two people that I know for sure were trampled... one gentleman was shot on the stop of the head, another gentleman was shot in the leg, a lady was shot in her side... another lady caught a round to the side of her head."
Aldean has issued a statement confirming he and his crew are all safe, and expressed his sorrow at Sunday evening's events.
"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," he wrote on Instagram.
"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. #heartbroken #stopthehate."
Flights from the city's McCarran International Airport were suspended following the shooting – although some flights have since resumed, according to a message on the airport's Twitter account advising people to "please monitor flight status with your airline" and "expect ongoing delays".
Part of the Strip is also closed off as emergency services continue their work.