Stephen Paddock has been named as the shooter who shot dead crowds of revellers at a country music event on the city’s world famous strip.
Some officers were seen taking cover behind their vehicles, while others carrying assault rifles ran into the Mandalay Bay Hotel and Casino.
Las Vegas Metropolitan Police Department (LVMPD) later confirmed that one suspect was dead and that he is believed to have acted alone.
The President took to Twitter shortly after sheriff Joe Lombardo confirmed the massacre was the deadliest mass shooting in US history.
Trump tweeted: “My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!”