At least 20 people have died and 100 are injured after a gunman opened fire on crowds at a music festival in Las Vegas, discharging hundreds of bullets using an automatic weapon.
Two festival-goers said they initially heard a noise "like firecrackers", but it became apparent a shooter was unloading "clip after clip" into the crowd. One man insisted there were "multiple shooters" involved, but police later ruled this out.
Video posted on social media appeared to show the moment the gunfire broke out during a song, stopping the performance and sending the crowd running.
The gunman was shot dead by police but officers are still searching for his roommate, Marilou Danley.
University Medical Center spokeswoman Danita Cohen said the Las Vegas hospital had taken in "several" people with gunshot wounds.
Another hospital spokesman said they had two dead and 24 injured.
Authorities shut down part of the Las Vegas Strip and Interstate 15.
Some flights destined for the McCarran International Airport were diverted due to incident.
Witnesses say country singer Jason Aldean was playing near the end of the concert when gunfire rang out but was unhurt.
