- 50 are confirmed dead
- Omar Mateen named as shooter
- Mateen was known to FBI
- Islamic State calls Omar Mateen "one of the soldiers of the caliphate in America".
- US president Barack Obama has said the nightclub shooting in Orlando was an "act of terror" and an "act of hate"
- Father of gunman claims religion was not the motive for killings
Read More:Nightclub gunman was 'peaceful' bodybuilder who wanted to join the police
Read More:Survivors describe escape from carnage while relatives face anxious wait
- Police confirm Mateen pledged allegiance to IS
The gunman who massacred 49 people at a US nightclub pledged his allegiance to Islamic State as he spoke on the phone to negotiators, police have confirmed.
Officers blasted a hole in the wall of the Pulse club in Orlando, Florida, in a desperate effort to save revellers as Omar Mateen held hostages in a toilet at the gay nightclub.
John Mina, chief of police at the City of Orlando Police Department, said Mateen barricaded himself in a toilet with around four or five hostages after shooting some of his initial victims and called the police, speaking in a "cool and calm" voice with crisis negotiators.
When he spoke about "bomb vests, about explosives" and made threats of an "imminent loss of life", police made the decision to blast through the wall with an armoured vehicle, which Mr Mina said saved "many, many lives".
Mr Mina also confirmed that when Mateen was on the phone to officers "there was allegiance to the Islamic State".
Authorities in Orlando confirmed that 49 people were killed in the shooting in the early hours of Sunday, with 53 others injured. All but one of the victims have been identified and the families of 24 have been informed.
Mateen, the 50th person to die, was killed by Swat officers when he opened fire at police after himself crawling out of the hole made to rescue the nightclubbers.
Islamic State radio calls Orlando mass killer Omar Mateen "one of the soldiers of the caliphate in America".
Al-Bayan Radio, a media outlet for the IS extremist group, hailed the attack that left 50 people dead, saying it targeted a gathering of Christians and gays and that it is the worst attack on US soil since the September 11, 2001, terrorist attacks.
Authorities say Omar Mateen opened fire with an AR-15 rifle at a gay nightclub early on Sunday before being killed in a shootout with police.
Another 53 people were wounded in the shooting.
As yet, IS has not officially claimed responsibility for the Orlando attack.
Doctors fear the death toll from the deadliest mass shooting in US history will rise, as the identities of the 50 people who were gunned down began to emerge.
Seven men and one woman have been named as victims of security guard Omar Mateen, 29, who massacred revellers and at least one employee at a gay nightclub in Orlando, Florida.
According to reports the body builder telephoned police and pledged allegiance to the Islamic State before he opened fire on the crowds with an assault rifle and handgun.
The caliphate has since claimed responsibility for the attacks described by President Barack Obama as an "act of hate".
Meanwhile it emerged that the New York-born killer, who worked for security giant G4S, had come under the gaze of counter-terror investigators several times in recent years.
More than 300 people were inside the Pulse nightclub at the time of the attack in the early hours of Sunday morning.
The killer, who also held hostages in a three-hour stand-off, died in a gunfight with Swat officers after they stormed the building. He had mortally wounded at least 50 victims and injured dozens more.
Officials said 39 people died in the venue and 11 at hospitals in the city where 53 people remain, most in a critical condition.
Orlando Mayor, Buddy Dyer, described the scene saying there was "blood everywhere".
The majority of the patients were taken to the Orlando Regional Medical Centre. Trauma surgeon Dr Mike Cheatham warned: "I think we will see the death toll rise."
Edward Sotomayor Jr, 34, Stanley Almodovar III, 23, Luis Omar Ocasio-Capo, 20, and Juan Ramon Guerrero, 22, were among the first victims to be named.
Peter O Gonzalez-Cruz, 22, and Eric Ivan Ortiz-Rivera 36, and Luis S Vielma, 22, were later added to the grim list along with Kimberly Morris, a 37-year-old who reportedly worked as a bouncer at the club.
Friend Lo Anthony wrote on Facebook that she "always had a smile on her face" and was "loved and adored by all".
Mr Obama earlier called the killings at the LGBT club as an "act of terror" and an "act of hate", describing Mateen as being "filled with hatred".
However the massacre served as a reminder of how easy it is for someone to access a weapon like a gun, allowing them to go on and shoot other people.
"We have to decide if that is the type of country we want to be. To actively to do nothing is a decision as well," the president said.
Mateen was known to the FBI after making inflammatory comments made to co-workers about extremism in 2013. He was questioned twice and investigated again in 2014 over potential links to an American suicide bomber, but the probe was dropped after he was deemed to be low-risk.
However he was not under surveillance and the FBI said he had legally purchased two firearms within the last week.
The 911 calls involving the shooter from Port St Lucie, Florida that featured conversations about the Islamic State before the massacre have been handed to investigators.
Mateen is believed to have pledged allegiance to the Islamic State leader, Abu Bakr al-Baghdadi during the call.
The Islamic State's Amaq news agency is understood to have issued a statement saying the massacre was "carried out by an IS fighter".
However US officials said it was possible that he was self-radicalised but not "under the command and control of ISIS."
An ex-wife described Mateen, reportedly a regular at an Islamic centre in the city, as a violent body builder who had a history of abusing steroids.
Meanwhile his father, Seddique Mir Mateen, told NBC news that his son had recently been angered after seeing two men kissing while out with his young son and denied the killings had a religious motive.
On Sunday evening vigils were held in Orlando and a group of around 100 people gathered in Paris in a show of solidarity.
British comedian James Corden, who hosted the Tony Awards in New York on Sunday evening, paid tribute to the victims and their loved ones saying "your tragedy is our tragedy".
British Prime Minister David Cameron earlier said he was "horrified" by the shooting, while Afghanistan's president, Ashraf Ghani said "targeting civilians is not justifiable under any circumstances whatsoever".
French president Francois Hollande said he "expresses the full support of France and the French with America's authorities and its people in this difficult time".
And Buckingham Palace said a personal message had been sent to President Obama, saying the Queen and Prince Philip were "shocked by the events in Orlando.
"Our thoughts and prayers are with all those who have been affected."
Mr Obama ordered flags at the White House and federal buildings to be flown at half-mast as a mark of respect for the victims. The Empire State Building in New York was left in darkness as a mark of sympathy on Sunday evening.
In the wake of the slaughter, a heavily-armed Indiana man was arrested on his way to a southern California gay pride parade.
Police stopped James Wesley Howell, 20, and discovered an arsenal of weapons in his vehicle including three assault rifles, high-capacity magazines and ammunition, and a five-gallon bucket with chemicals that could be used to make an explosive device.