The suspected gunman in a Las Vegas shooting that saw more than 50 people killed is thought to have killed himself before police Swat team officers breached the room he was in.

Some 22,000 people were in the crowd when the man - identified as Stephen Paddock - opened fire, sending panicked people fleeing the scene, in some cases trampling one another, as law enforcement officers scrambled to locate and kill the gunman. Shocked concertgoers, some with blood on their clothes, wandered the streets after the attack.

Paddock opened fire from his hotel room on the 32nd floor of the Mandalay Bay Hotel on Sunday evening at approximately 10:08pm The victims were across the street attending the Route 91 Harvest Festival concert when bullets rang out. LVMPD SWAT responded to the call, breached the hotel room and found the suspect dead, police said in a statement.

At least 406 people were taken to area hospitals with injuries, the Las Vegas Metropolitan Police said.

Paddock was not believed to be connected to any militant group, Clark County Sheriff Joseph Lombardo told reporters.

“We have no idea what his belief system was,” Mr Lombardo said. “We've located numerous firearms within the room that he occupied.”

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

Swat teams quickly descended on the concert and the casino after the attack started, and officers used explosives to get into the hotel room where the suspect was inside, authorities said.

“What we are going to try to do as best we can is to get our first responders back on their feet and responding and conducting a proper investigation to ensure that we have the safety of this community at heart,” Sheriff Lombardo said.

Country music star Jason Aldean was performing Sunday night at the end of the three-day Route 91 Harvest Festival in front of a crowd of 22,000 when the gunman opened fire from inside the Mandalay Bay Hotel and Casino.

Aldean was in the middle of a song when the shots came rapidly: Pop-pop-pop-pop. Video of the shooting then showed Aldean stopping and the crowd getting quiet as if it were unsure of what had just happened.

The gunman paused and then fired another volley, the muzzle flashes visible from the casino, as more victims fell to the ground while others fled in panic. Some hid behind concession stands, while others crawled under parked cars.

In addition to Paddock, police said they located a woman who may have been his roommate — Marilou Danley, 62. Lombardo said they believe this was a “lone wolf” attack.

“It's a devastating time,” Sheriff Lombardo said.

President Donald Trump has extended condolences to the victims of the shooting in Las Vegas and their families.

In a tweet, Mr Trump offered “My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!”

The White House said Mr Trump was expected to make remarks Monday morning, though details were not finalised.

White House spokeswoman Sarah Huckabee Sanders said Mr Trump was “briefed on the horrific tragedy in Las Vegas.”

Ms Sanders said that “we are monitoring the situation closely and offer our full support to state and local officials. All of those affected are in our thoughts and prayers."​