A country music festival on the Las Vegas Strip did not end joyfully, as shooting that broke out on the last night of the 3-day event left at least 20 people dead.

Two deaths were reported after the shooting, but more deaths occurred later.

At least 24 were hospitalised after the shooting at the Route 91 Harvest festival, a sold-out event attended by thousands and featuring top acts such as Eric Church, Sam Hunt and Jason Aldean.

The police said one suspect was down.

Witnesses on social media said the shooting broke out on the last night of the three-day festival as U.S. media, including Fox News, reported that Aldean was performing on Sunday night when the rampage began.

He was however bundled safely off stage at the event outside the Mandalay Bay Resort and Casino in the Nevada gambling mecca.

The spokeswoman for the University Medical Centre hospital said 14 of the wounded were in a critical condition.

“Confirming that one suspect is down. This is an active investigation. Again, please do not head down to the Strip at this time,” Las Vegas Metropolitan Police Department said on Twitter.

Las Vegas shooting leave 20 dead

It was not immediately clear whether the suspect was killed or injured. Police said on Twitter that at this time they did not believe there are any more shooters.

Las Vegas is an internationally renowned major resort city, known primarily for its gambling, shopping and entertainment.

Video on the festival’s website showed stage set up outside the front of the Mandalay Bay.

The hotel is near McCarran International Airport, which said on Twitter it had temporarily halted flights after the shooting.

Later, the airport said that some flights had resumed.

One Twitter user posted that the casino hotel was on lockdown, while another, citing police scanners, said two gunmen who had shot at a bodyguard and police were on the 32nd floor, although there was no confirmation from police.