At least 50 people have been killed and dozens injured after a gunman opened fire at a gay nightclub in Orlando, in an incident that lasted three hours. What do we know about what happened?
How the incident unfolded
The attack began at about 02:00 local time (06:00 GMT), said Police Chief John Mina.
Pulse, which is one of the biggest nightclubs in Orlando, Florida, was holding a Latin-themed event that was nearing its end when a man opened fire inside.
Shortly afterwards, the nightclub posted on its Facebook page: “Everyone get out of pulse and keep running.”
Police sources have told US media the gunman was in possession of a suspicious device strapped to his body.
There was an exchange of fire with a police officer working at the club, but it is unclear whether that was inside or outside the venue.
A hostage situation developed and at 05:00 local time (09:00 GMT), officers stormed the building and detonated a “controlled explosion”.
The gunman was killed and police said at least 50 people are also dead, making it the worst mass shooting in recent US history.
That figure could rise, with at least 53 wounded people taken to hospital.
Officials have named the suspect as Omar Mateen, a 29-year-old from Fort Pierce, a city about two hours drive south of Orlando, in St Lucie County.
An FBI spokesman said the gunman appeared to “have leanings towards” radical Islamist ideology but it was not yet clear whether this was a case of domestic or international terrorism.
Police said he had been armed with an assault-type rifle, a handgun and some type of suspicious device.
They have not said whether they think the nightclub was targeted because it is gay.
US Congressman Alan Grayson said it was “no coincidence” the attack happened in a gay club.
And Mr Mateen’s father told NBC News his son became very angry when he saw two men kissing recently in Miami.
There were about 320 people inside the club during the shooting, according to the Orlando Sentinel. Some have been speaking about what they witnessed.
“All you saw is people running and screaming and there were bodies in the parking lot where bodies were being tagged,” Christopher Hansen told CNN. “It was like a scene from a horror movie.”
Jon Alamo said he saw a man holding a weapon walking into the room he was in.
“I heard 20, 40, 50 shots, he said. “The music stopped.”
Has there been political reaction?
A statement from the White House said the president had been briefed about the shooting.
“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, and directed that the federal government provide any assistance necessary to pursue the investigation and support the community.”
The presumptive Republican presidential nominee, Donald Trump, tweeted: “Really bad shooting in Orlando. Police investigating possible terrorism. Many people dead and wounded.”
His Democratic rival, Hillary Clinton, tweeted: “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.”
Florida Senator Marco Rubio told CNN the gunman was an “animal” whose act of violence showed that “this is the new face of the war on terror”.
He also paid tribute to the police officers who “saved lives” by raiding the club to bring the attack to an end.