At least 59 people were killed and more than 520 injured when a 64-year-old gunman with an arsenal of at least 10 rifles fired upon a Las Vegas country music festival on Sunday, raining down shots from a 32nd-floor window for several minutes before killing himself.

Some 22,000 people were in the crowd when a man who police have identified as Stephen Paddock (64) opened fire, sparking a panic in which some people trampled on others, as law enforcement officers scrambled to locate the gunman.

US president Donald Trump has said the Las Vegas massacre was an act of “pure evil” in a live televised speech from the White House. Later, a moment of silence in honour of the victims was observed by the president and his wife Melania on the White House lawn.

The death toll, which police emphasised was preliminary, makes the massacre the deadliest mass shooting in US history, worse than last year’s killing of 49 people at an Orlando nightclub.

Federal officials have said there was no evidence to link Paddock to international militant groups. “As this event unfolds, we have determined to this point no connection with an international terrorist group,” FBI special agent in charge Aaron Rouse said.

A senior US administration official discounted a claim by Islamic State that it was responsible for the attack. The terror group also claimed the attacker had converted to Islam a few months ago.

“The Las Vegas attack was carried out by a soldier of the Islamic State and he carried it out in response to calls to target states of the coalition,” the group’s news agency Amaq said in reference to the US-led coalition fighting the group in the Middle East.

After the attack, shocked concertgoers, some with blood on their clothes, wandered the streets in Las Vegas.

No criminal record

Police said they had no information about Paddock’s motive, and that he had no criminal record and was not believed to be connected to any militant group. Paddock killed himself before police entered the Mandalay Bay hotel room he was firing from, Clark County Sheriff Joseph Lombardo told reporters.

“We have no idea what his belief system was,” Mr Lombardo said. “We believe the individual killed himself prior to our entry,” he told a news conference.

Earlier reports indicated Paddock had been shot dead by police.

Mr Lombardo said there were more than 10 rifles in the room where Paddock killed himself. He had checked into the hotel on Thursday. Paddock was not known to law enforcement, Lombardo said.

Eighteen additional firearms and explosives were retrieved from the gunman’s house in Mesquite, Mr Lombardo added.

The dead included one off-duty police officer, Mr Lombardo said. Two on-duty officers were injured, including one who was in stable condition after surgery and one who sustained minor injuries, he added. Police warned the death toll may rise.

Police are still finding people who had taken cover during the attack, Mr Lombardo said. “It’s going to take time for us to get through the evacuation phase,” he added.

Flags at half-mast

Mr Trump, in his televised speech, said he had directed US flags to be flown at half-mast around the country, and that he would visit Las Vegas on Wednesday.

He said, the FBI and Department of Homeland Security were working to assist the investigation. “I want to thank the Las Vegas Metropolitan Police Department and all emergency responders,” he said, for their role in saving lives and prevention of further loss of life.

He thanked police for finding the shooter so quickly, for which he would always be “thankful and grateful”, and said their actions were what “true professionalism is all about”.

Regarding victims’ families, he said: “We cannot fathom their pain, we cannot imagine their loss. To the families of the victims we are praying for you and we are here for you.

“The bonds of citizenship and our unity cannot be shattered by evil and our bonds cannot be shattered by violence. It is our love that defines us today and always will forever. I know we are searching for some kind of meaning in the chaos. The answers do not come easily.”

Referring to scripture, he said: “Melania [Trump] and I are praying for every single American hurt in this terrible, terrible attack. We pray for the day when evil is banished. May god bless the souls and the lives of the lost. May god give us the strength to carry on.”

He did not make any reference in his speech to gun ownership rights in the US, an issue of consistent controversy in the country over many years.

Video courtesy of Drew Akioshi. He was attending the concert at mandalay bay when shooting started. pic.twitter.com/mbyh9Y387q — David Sakach (@davidsakach) October 2, 2017 Please do not livestream or share tactical positions of our officers on scene. This may put emergency responders in danger. — LVMPD (@LVMPD) October 2, 2017

Sustained gunfire

Video of the attack showed panicked crowds fleeing as sustained rapid gunfire ripped through the area.

“It sounded like fireworks. People were just dropping to the ground. It just kept going on,” said Steve Smith, a 45-year-old visitor from Phoenix, Arizona, who had flown in for the concert. He said the gunfire went on for an extended period of time.

“Probably 100 shots at a time. It would sound like it was reloading and then it would go again,” Mr Smith said. “People were shot and trying to get out. A lot of people were shot.”

Las Vegas’s casinos, nightclubs and shopping draw some 3.5 million visitors from around the world each year and the area was packed with visitors when the shooting broke out shortly after 10pm local time (5am Irish time).

Shares of US casino operators fell in early trading on Wall Street, with MGM Resorts International, which owns the Mandalay Bay, down 4 per cent. Melco Resorts & Entertainment Ltd, Wynn Resorts Ltd and Las Vegas Sands Corp each fell 1 to 2 per cent.

Hundreds of shots

Mike McGarry, a 53-year-old financial adviser from Philadelphia, was at the concert when he heard hundreds of shots ring out.

“It was crazy – I laid on top of the kids. They’re 20. I’m 53. I lived a good life,” Mr McGarry said. The back of his shirt bore footmarks, after people ran over him in the panicked crowd.

The shooting broke out on the final night of the three-day Route 91 Harvest festival, a sold-out event featuring top acts such as Eric Church, Sam Hunt and Jason Aldean.

“Tonight has been beyond horrific,” Aldean said in a statement on Instagram. “It hurts my heart that this would happen to anyone who was just coming out to enjoy what should have been a fun night.”

Mr Trump offered his condolences to the victims via a post on Twitter early Monday.

“My warmest condolences and sympathies to the victims and families of the terrible Las Vegas shooting. God bless you!” Mr Trump said.

The rampage was reminiscent of a mass shooting at a Paris rock concert in November 2015 that killed 89 people, part of a wave of co-ordinated attacks by Islamist militants that left 130 dead.

The concert venue was in an outdoor area known as Las Vegas Village, across the Strip from the Mandalay Bay and the Luxor hotels.

“Our thoughts & prayers are with the victims of last night’s tragic events,” the Mandalay Bay said on Twitter.

Police had located two cars that belonged to the suspect.

He said rumours of other shootings or explosives such as car bombs in the area were false.

A witness named Christine told CNN both she and her husband had separately taken shooting victims to two hospitals, the University Medical Centre and the Sunrise Hospital and Medical Centre.

“The shots just kept coming,” she said. “Everyone was telling us ‘run, run as fast as you can’.”

The United States has seen a series of deadly mass shootings in recent years. Prior to Orlando, the deadliest occurred in April 2007, when a gunman killed 32 people at Virginia Tech university, and in December 2012, a man killed 26 young children and educators at Sandy Hook Elementary School in Newtown, Connecticut.

The suspected shooter’s brother, Eric Paddock, said the family was stunned by the news.

“We have no idea. We’re horrified. We’re bewildered and our condolences go out to the victims,” Eric Paddock said in a brief telephone interview, his voice trembling. “We have no idea in the world.”

Mr Paddock told CBS News his brother was “not an avid gun guy at all”. He added: “The fact that he had those kinds of weapons is just ... where the hell did he get automatic weapons? He has no military background or anything like that.

“He’s a guy who lived in a house in Mesquite and drove down and gambled in Las Vegas.”

‘Senseless tragedy’

Meanwhile the pope called the shooting a “senseless tragedy” and said he would pray for victims.

The Vatican secretary of state sent a telegram of condolence to the bishop of Las Vegas, saying Pope Francis was “deeply saddened” to learn of the shooting.

The telegram said the pope praised the efforts of police and emergency crews.

Las Vegas police also said they have determined that the woman thought to have been the gunman’s room-mate is no longer considered a “person of interest” in the inquiry.

Officers do not believe 62-year-old Marilou Danley was involved in the shooting.

Meanwhile, heavily armed police were searching the Nevada retirement-community home of Paddock.

Mesquite Police chief Troy Tanner said officers entered the property where the 64-year-old lived.

He said Ms Danley was not at the house and police saw “no movement” inside the one-storey, three-bedroom home in the Sun City Mesquite retirement community, about 80 miles north of Las Vegas.

Mr Tanner said detectives are at the scene in the resort community, located near the Arizona state line.

Attack ‘appalling’

President Michael D Higgins has said the Las Vegas attack was appalling and sent shock around the world.

No Irish people are so far known to have been killed or injured in the indiscriminate shooting at the festival.

Mr Higgins said: “The appalling massacre of music lovers of different generations, at a public event in Las Vegas, will have shocked people all over the world.

“On behalf of the people of Ireland, may I express my deepest sympathies to all those bereaved and affected by this brutal tragedy.

“Our thoughts in Ireland, and of the Irish in the United States, are with the people of Nevada and the United States at this tragic time.”

Minister for Foreign Affairs Simon Coveney condemned the shootings and expressed condolences on behalf of Ireland.

“This was a savage and brutal attack targeting innocent festival-goers,” he said.

“I wish to express my heartfelt condolences and those of the Irish people to the families of the victims, those who were injured and to the people and the authorities of the United States on this tragic day.”

Irish diplomats in the consulate general in San Francisco and the honorary consulate in Las Vegas are monitoring the situation.

The Department of Foreign Affairs issued a contact number for families in Ireland who have concerns about relatives to ring the consular assistance unit on +353 1 408 2527.

Reuters/PA