LATEST: Ex-FBI profiler thinks they may need to carry out 'psychological autopsy' on Stephen Paddock

LATEST: As he prepared to travel to Las Vegas, Donald Trump said it was a "sad day".

UPDATE 2.42pm: As he prepared to travel to Las Vegas, Donald Trump said it was a "sad day".

The US president added: "It's a very sad thing. We are going to pay our respects and to see the police who have done really a fantastic job in a very short time."