In the worst mass shooting in US' history, at least 50 people were killed and 53 others injured when a "lone wolf" gunman opened fire early on Sunday in a gay nightclub in Orlando, Florida, where a state of emergency has been declared.
The gunman, named by officials as Omar Mateen, 29, was killed by a SWAT team after he took hostages at Pulse, a popular gay night club.
It is believed that the suspect, who was a US citizen from the Florida town of Port St Lucie and was of Afghan descent, was not on a terrorism watch list, although he was being investigated for an unrelated criminal act, BBC reported.
Officials said the killings were likely to be ideologically motivated, though there was no information that the gunman was associated with a particular group.
He was armed with an assault rifle, a handgun and an unspecified "device", said officials.
"It appears he was organised and well-prepared," Orlando Police Chief John Mina said.
The shooter's father told NBC News: "This has nothing to do with religion."
Florida gov: This is an attack on Orlando, attack on America, attack on every one of us. https://t.co/gFudOOa6oy https://t.co/rCJf5I54Y2
— CNN (@CNN) June 12, 2016
Mir Seddique said Omar Mateen had been angry when he saw two men kissing in Miami recently.
"We are saying we are apologising for the whole incident. We weren't aware of any action he is taking. We are in shock like the whole country," Seddique told NBC News .
US President Barack Obama was briefed on the mass shooting, which police described as an act of terrorism.
"Our thoughts and prayers are with the families and loved ones of the victims. The President asked to receive regular updates as the FBI, and other federal officials, work with the Orlando Police to gather more information," said a statement by Barack Obama's press secretary.
A survivor of the Orlando nightclub attack describes the panicked aftermath https://t.co/2YHp5wbDJAhttps://t.co/JdHjOzZWXC
— CNN (@CNN) June 12, 2016
US Congressman Alan Grayson said it was "no coincidence" the attack happened in a gay club.
Relatives were gathering at local hospitals desperate for news of their loved ones.
Many had received calls and texts from loved ones inside the club as the siege began, and some have heard nothing since.
Horrific incident in FL. Praying for all the victims & their families. When will this stop? When will we get tough, smart & vigilant?
— Donald J. Trump (@realDonaldTrump) June 12, 2016
The death toll given by Mayor Dyer means that the Orlando attack surpasses the 2007 massacre at Virginia Tech which left 32 people dead.
"Today we are dealing with something that we never imagined and is unimaginable," he said, adding that there was "an enormous amount of havoc" and "blood everywhere".
Woke up to hear the devastating news from FL. As we wait for more information, my thoughts are with those affected by this horrific act. -H
— Hillary Clinton (@HillaryClinton) June 12, 2016
"Because of the scale of the crime I've asked the [Florida] governor to declare a state of emergency," he said.
Orlando shooting sparks gun control, language debates https://t.co/6auAoSQ8Rk https://t.co/sUll572G4y
— CNN (@CNN) June 12, 2016
"We're also issuing a state of emergency for the city of Orlando so that we can bring additional resources to bear to deal with the aftermath."
EX-WIFE OF ORLANDO GAY NIGHTCLUB SHOOTER SAYS 'HE BEAT ME'
The ex-wife of the 29-year-old man suspected of killing 50 people in a Orlando nightclub early on Sunday said he was violent and mentally unstable and beat her repeatedly while they were married.
The ex-wife said she met Omar Mateen online about eight years ago and decided to move to Florida and marry him, Independent.co.uk reported.
At first, the marriage was normal, she said, but then he became abusive.
"He was not a stable person," said the ex-wife, who spoke on the condition of anonymity because she feared for her safety in the wake of the mass shooting.
"He beat me. He would just come home and start beating me up because the laundry was not finished or something like that."
While the FBI has not identified Mateen publicly, US law enforcement officials said his identification was found on the body of the suspected killer who was armed with a handgun and an assault rifle.
Mateen's ex-wife said his family was from Afghanistan, but her ex-husband was born in New York. His family later moved to Florida.
She said she was having a difficult time when she first met him and decided to move to Florida to be with him. The two married in March 2009 and moved into a two-bedroom condominium in Fort Pierce, Florida that Mateen's family owned.
"He seemed like a normal human being," she said, adding that he was not very religious and worked out at the gym often.
She said in the few months they were married he gave no signs of having fallen under the sway of radical Islam.
She said he owned a small-caliber handgun and worked as a guard at a nearby facility for juvenile delinquents.
"He was a very private person," she said.
ORLANDO GUNMAN USED AR-15 'WEAPON OF CHOICE FOR MASS SHOOTERS'
Gunman Omar Mateen was armed with an AR-15-type assault rifle, which has become the signature weapon of mass killers in the US.
Known as "America's gun," it is owned by around 3.7 million American households, making it the country's most popular rifle, reported the Telegraph (UK) online.
The military-grade weapon was used by Adam Lanza in December 2012 to shoot dead 26 people at Sandy Hook in Newtown, while the San Bernardino terrorists used AR-15s when they killed 14 people in December 2015.
It was also used to kill nine people at Umpqua Community College in October 2015.
And in July 2012 James Eagan Holmes used an AR-15-type assault rifle to kill 12 people in Aurora, wounding a further seventy.
The sale of semiautomatic weapons is hugely controversial in America as the rapid fire mode would allow a rogue gunmen to kill dozens of people in a matter of seconds.
It was speculated on Sunday that Mateen, 29, would only have needed to reload once during his killing spree due to the weapon's large clip size.
In the state of Florida, anyone over the age of 18 can buy an AR-15 as no state permit is required. The same goes for pistols and shotguns.