At least 58 people have been killed in the Las Vegas mass shooting, with 515 people injured, according to police.

The number may have increased to 59 in the few minutes it took Clark County Sheriff Joseph Lombardo to brief reporters.

“As the hours go by, that number continues to increase," Mr Lombardo said.

The night before, a Nevada resident had opened fire on a concert near Mandalay Bay Resort and Casino. Mr Lombardo said the shooter used a hammer-like device to break open the window of his 32nd-story room and rain gunfire on the concert-goers. Police believe he was armed with at least 10 weapons.

The man identified as the shooter, 64-year-old Stephen Paddock, killed himself after the shooting, police said.

Las Vegas shooting – in pictures Show all 15 1 /15 Las Vegas shooting – in pictures Las Vegas shooting – in pictures People scramble for shelter at the Route 91 Harvest country music festival after gun fire was heard Getty Las Vegas shooting – in pictures People carry a person at the Route 91 Harvest country music festival after shots were fired David Becker/Getty Las Vegas shooting – in pictures People run from the Route 91 Harvest country music festival after gun fire was heard David Becker/Getty Las Vegas shooting – in pictures A handout photo released via Twitter by Eiki Hrafnsson (@EirikurH) showing concertgoers running away from the scene (C) after shots range out at the Route 91 Harvest festival on Las Vegas Boulevard EPA/Eiki Hrafnsson Las Vegas shooting – in pictures People lie on the ground at the Route 91 Harvest country music festival after hearing gun fire Getty Las Vegas shooting – in pictures A man in a wheelchair is taken away from the Route 91 Harvest country music festival after hearing gun fire David Becker/Getty Las Vegas shooting – in pictures People stand on the street outside the Mandalay Bay hotel near the scene of the Route 91 Harvest festival on Las Vegas Boulevard EPA/Paul Buck Las Vegas shooting – in pictures FBI agents confer in front of the Tropicana hotel-casino after a mass shooting during a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Las Vegas police run by a banner on the fence at the Route 91 Harvest country music festival grounds after shots were fired David Becker/Getty Las Vegas shooting – in pictures An injured person is tended to in the intersection of Tropicana Ave. and Las Vegas Boulevard after a mass shooting at a country music festival Ethan Miller/Getty Las Vegas shooting – in pictures Metro Police officers pass by the front of the Tropicana hotel-casino after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures A woman sits on a curb at the scene of a shooting outside of a music festival along the Las Vegas Strip AP/John Locher Las Vegas shooting – in pictures A cowboy hat lays in the street after shots were fired near a country music festival in Las Vegas Getty Las Vegas shooting – in pictures Las Vegas Metro Police and medical workers stage in the intersection of Tropicana Avenue and Las Vegas Boulevard South after a mass shooting at a music festival on the Las Vegas Strip Reuters/Las Vegas Sun/Steve Marcus Las Vegas shooting – in pictures Sheriff Joe Lombardo (2-R) speaking during a press briefing in the aftermath of the active shooter incident on Las Vegas Boulevard EPA

Mr Lombardo maintained the shooter acted alone, although one woman remains a person of interest. The woman, Marilou Danley, is out of the country, but has made contact with officers. Mr Lombardo said the department plans to "engage" her as soon as she returns.

Mr Paddock had no prior criminal record, Mr Lomabardo said.

While ISIS has claimed responsibility for the attack, an FBI spokesperson said the agency had determined no connection to any international terrorist organisation.

Las Vegas shooting witness recounts woman telling crowd "they were all going to die" before attack

Mr Lomabrdo said the law enforcement agencies had completed their search of Mr Paddock's room at Mandalay Bay, and were turning their attention to his property in northern Nevada. FBI agents were on the scene and awaiting a search warrant at the time of the press conference.

Clark County District Attorney Steve Wolfson underscored the severity of the incident, which has been deemed the deadliest mass shooting in US history.

"This is a weapon, and a man, of mass destruction," Mr Wolfson said.

FBI agents confer in front of the Tropicana hotel-casino on October 2, 2017, after a mass shooting during a music festival on the Las Vegas Strip in Las Vegas, Nevada (REUTERS/Las Vegas Sun/Steve Marcus)

Las Vegas Mayor Carolyn Goodman praised the actions of first responders and the everyday residents of Las Vegas. She said off-duty police officers in the crowd had helped victims find shelter, and passerby had ushered those fleeing the scene into their cars.

"This is a crazed lunatic full of hate. We don’t know much about his background," she said of Mr Paddock. "But it’s certainly not an extension about what we believe in."

Congresswoman Dina Titus, who represents Nevada's first congressional district, offered similar praise.

“That’s the kind of people we have here in Las Vegas, who are willing to reach out and help one another," she said.