The development follows Sunday’s shooting at Mandalay Bay Hotel towards, when gunman Stephen Paddock, 64, opened fire from the 32nd floor of the hotel against during open-air music festival at the hotel on Sunday evening.
Here are the things we so far know about the shooter
Stephen Paddock lived in a community of senior citizens in the small town of Mesquite, north-east of Las Vegas.
He reportedly lived with a woman called Marilou Danley who is out of the country in Japan, and does not appear to be involved, police said.
Police found 23 guns in his hotel room.
Polie also found 19 “additional firearms, some explosives and several thousand rounds of ammo, along with some electronic devices.
He has a second house in northern Nevada which Swat teams are due to check for booby-traps before carrying out a search, Sheriff Lombardo said.
Investigators have found no link to international terrorism, despite a claim from so-called Islamic State. Some investigators have suggested psychological issues, but there is no confirmation of this.
There is no confirmation that Paddock may have suffered some psychological disturbances.
The shooter was not known to police.
He had purchased firearms at his store in North Las Vegas in the spring of this year, meeting all state and federal requirements, including an FBI background check.
The Islamic State (ISIS) has claimed to be behind the attack, saying Paddock had converted to Islam some months ago, but there is no evidence to support that claim. The group moreover, has made unsubstantiated claims in the past.
FBI Special Agent Aaron Rouse told a news conference: “We have determined at this point no connection to an international terrorist organisation.”
Who are the victims?
The authorities have yet to confirm the identities of any of the 58 killed.
Jordan McIldoon, 23, from British Columbia in Canada, has been identified as a victim of the attack by CBC News.
A nurse, Sonny Melton, of Big Sandy, Tennessee, has been named as another victim by The Jackson Sun newspaper. In a Facebook post, his wife, Dr Heather Gulish Melton, said she “lost my true love and knight in shining armor. I appreciate the prayers but I just need some time.”
An off-duty Las Vegas police officer was another of those who died.
Former congresswoman Gabrielle Giffords, who survived a shooting six years ago, called for political leaders in Washington to introduce tougher gun laws following the Las Vegas attack.
Her husband Mark Kelly read out a joint statement on the steps of the Capitol saying thoughts and prayers from the White House were not enough to stop the next shooting.
A version of this report appeared on BBC news