Over 50 people have been confirmed killed and 400 others injured in the US city of Las Vegas  in what is said to be the worst mass shooting in American history.

A lone gunman identified by police as 64-year-old Stephen Paddock opened fire from a perch high up in the Mandalay Bay Resort and Casino in Las Vegas on a concert crowd of some 22,000 people on  Sunday night.

According to one eye-witness, the nonstop gunfire, sent bystanders outside the resort on the Vegas strip ducking for cover and scrambling for their lives. Among the dead are off-duty police officers who were attending the country musical concert.

Eye witnesses say the dastardly act was executed with automatic gunfire judging from the sound of the gun which many mistook at first for fireworks.

Bystanders made makeshift stretchers out of police barricades, plugged wounds with their hands and used their clothing to try to hold back the blood of the hundreds of people who had deep injuries.

In the wake of the shooting, the Las Vegas Police Department said the suspected gunman, who was believed to be a local resident, was in a room on the 32nd floor of the Mandalay Bay Hotel.When Police eventually gained access to his room,  Stephen Paddock was found dead with bullet wounds, suggesting that he most probably shot himself.

The motive of his action, according to law enforcement, is still unclear. So far, there have been no ties to international terror.