US police have said one suspect is "down" after a mass shooting at a country music festival on the Las Vegas Strip in which at least two people were killed and dozens of others injured.
University Medical Centre spokeswoman Danita Cohen said 26 people had been admitted to the hospital. Of those, at least two had died and 12 were in a critical condition. The rest are being assessed.
Dozens of patrol vehicles descended on the Strip after authorities received reports of an active gunman near the Route 91 Harvest Festival.
Some officers took cover behind their vehicles while others carrying assault rifles ran into the Mandalay Bay Hotel and Casino.
Authorities shut down part of the Las Vegas Strip and Interstate 15.
Concert-goers reported seeing muzzle flashes from the upper floors of the Mandalay Bay hotel-casino across Las Vegas Boulevard from the music event and the sound of what they described as automatic gunfire.
Witnesses said they saw multiple victims as they fled the gunfire raining down on the concert venue.
Some later huddled in the basement of the nearby Tropicana hotel-casino.
Some flights destined for McCarran International Airport were diverted due to the incident.
Witnesses said country singer Jason Aldean was playing near the end of the concert when gunfire rang out.
A concert-goer said he heard what sounded like fireworks while he was watching Aldean's performance.
Kodiak Yazzi said the music stopped temporarily and then started up again before another round of pops sent the performers ducking for cover and fleeing the stage.
As the 40,000 fans in the crowd began to flee, the 36-year-old took cover and said he saw flashes of light coming from the Mandalay Bay hotel tower high above.
The bursts of pops would start and stop for more than five minutes.
He said he saw dozens of ambulances as he ran for safety. He later got a Lyft driver to take him home to suburban Henderson.