"We have in excess of 100-plus injured and excess of 20-plus that have died at this point," local reports quoted  Las Vegas Metro Police Sheriff Joseph Lombardo as saying.

The sherriff said the suspect is dead.

Police said the shooter was a local man, and his companion is being sought.

Earlier, the metro police had tweeted :   "At this time we do not believe there are any more shooters."

SWAT teams were sent to the 32nd floor of the Mandalay Bay where at least one gunman was believed to be located.

The authorities later confirmed there were no other gunmen.

The New York Times said 26 people were admitted to the University Medical Center.  At least two of those people died and 12 were in a critical condition.

The attack came during the last performances on the final night of the  three-day country music festival on an 15-acre lot across Las Vegas  Boulevard from Mandalay Bay.

It appeared the shooter was firing down at people from upper-level rooms of Mandalay Bay.

Local reports quoted a concert-goer as saying that  he heard what sounded like fireworks while he was watching Jason Aldean's performance at the Route 91 Harvest country music festival Sunday night.

Following the deadly  incident, all planes were temprarily grounded at the Las Vegas airport. However, flights resumed after some time.

Witnesses on social media said the shooting broke out on the last night of the three-day Route 91 Harvest festival, a sold-out event attended by thousands and featuring acts such as Eric Church, Sam Hunt and Jason Aldean.

Image: twitter.com/LVMPD