Daniel Gilroy, who worked with Omar Mateen at G4S, told multiple news outlets the man repeatedly made threats of violence.

"He talked about killing people all the time,'' he said.

"He was an angry person, violent in nature, and a bigot to almost every class of person." 

Mr Gilroy said he reported Mateen's behavior to his bosses and eventually quit working with him.

"I kind of feel a little guilty that I didn't fight harder," he said. "If I didn't walk away and I fought, then maybe 50 people would still be alive today."

Here in the UK, the Archbishops of York and Canterbury have issued a joint statement calling on Christians to support lesbian, gay, bisexual, trans and intersex people.

Stars react to mass shooting in Orlando nightclub, including JK Rowling who said one of those killed worked on a Harry Potter ride at Universal Studios.

Although attention is focused on Orlando, where the deadliest mass shooting in US history has taken place, Americans continue to be killed and wounded in gun violence elsewhere.

In Chicago, seven people have been killed and 32 - including a five-year-old girl - injured in shootings since Friday night, local TV reports.

In his interview with CNN, Mr Trump accused Muslim communities of not reporting potentially dangerous people.

"People that knew him, the ex-wife, other people. They don't report them. For some reason the Muslim community does not report people like this."

Mateen's ex-wife told the Washington Post, external he was not particularly religious during their short marriage in 2009, but that he was abusive and she fled.

Trump then suggested broader surveillance against Muslims in the US.

"We have to look at the mosques... and we have to look at the community,"

Republican presidential candidate Donald Trump has reiterated his stance on immigration to the US in light of the Orlando shooting. 

Speaking to CNN, he said "we have to stop people coming in from Syria", saying US will have a "problem we have never seen before".

"We have people born here who have caused tremendous difficulties. We have had people coming in and we have, by the way, thousands and thousands of people pouring into the country right now that have the same kind of hate," he said.

Gunman Omar Mateen was a US citizen, born in New York, of Afghan descent.

When asked about gun control, Mr Trump said having additional guns in the club would have helped minimise the tragedy. 

"If you had some guns in the club, if you had guns on the other side you wouldn't have had the same tragedy," he said.

Image source, Reuters

So far, 26 of the 49 victims in Orlando have been named: 22 men and four women aged between 20 and 50.

Tributes to them have been paid by family and friends - read more about their stories here.

So to recap that news conference in Orlando. 

Police have provided some additional details of the initial response to the Pulse shooting and the subsequent rescue mission. 

Police chief John Mina says there was an off-duty officer working at Pulse who heard gunfire and engaged in a gun battle with the killer near one of the entrances.

Additional officers arrived shortly after, entered the club and engaged in another shoot-out with Mateen, forcing him to stop shooting and retreat to the bathroom with several hostages. 

"Dozens and dozens" of people were then released from the club.

Chief Mina said that statements made by the suspect and coming from people inside then convinced police that further loss of life was imminent.

Officers tried to blow a hole in the wall, but when that failed a "Bearcat" armoured vehicle was driven into the side of the nightclub, creating a hole. It was then that Mateen came out shooting and was shot dead.

Flags have been lowered to half-mast in the grounds of the Washington Monument in memory of those killed in Orlando.

Image source, Getty Images

Hillary Clinton, the presumptive Democratic presidential candidate, has said "we have to defend our country from lone wolves".

In an interview to US broadcaster CNN, she said "it's a complex challenge" but that "we can do it".

So-called Islamic State (IS) has issued a message linking the Orlando attacker to the group but questions remain over the extent of the links or any co-ordination between them.

Some more quotes from Mayor of Orlando, Buddy Dyer. He said: "We won't be defined by this. We will not be defined by the act of a cowardly hater. We will be defined by how we respond, how we treat each other and this community has already stepped up to do that."

Police chief John Mina has been taking questions from reporters. He says the killer was "cool and calm" while on the telephone to police. He says Matten made a pledge of allegiance to so-called Islamic State while on the phone. 

He retreated to a bathroom in the nightclub with hostages, he said, where he continued negotiating with police.

He said: "He was't really asking for a whole lot, we were doing most of the asking."

He says it was a "tough decision" to send armed officers into the nightclub, but said the decision saved lives, saying police believed there was a risk of "imminent loss of lives".

"Dozens and dozens of people were saved when we made that initial entry," he said.

FBI special agent Paul Wysopal was asked about what officials knew about Omar Mateen, the Orlando nightclub shooter, before the attack. But he said he couldn't answer questions yet.

He said the investigation would now work "forward and back".

It has been revealed that the FBI interviewed Mateen twice in 2013-14 after he made "inflammatory remarks" to a colleague, before closing its investigation.

He was not on a terrorism watch list.

Here is what we know about the shooter.

Officials have confirmed that 49 people were killed inside the nightclub and that the 50th person to die was suspect Omar Mateen.

FBI special agent Paul Wysopal has spoken, saying "our focus is to get the truth". 

He says there is the possibility of criminal prosecutions later in the investigation, so he is not providing many more details. 

But he says "no stone will be left unturned". He says it may take "some time to get accurate information" to provide to the public.

As a news conference continues in Orlando, the US attorney Lee Bentley has said that "if anyone else was involved" in the nightclub attack "they will be prosecuted".

He said other people are being investigated.

Police chief John Mina has been giving dramatic details of the armed mission to respond to the shooting at the Pulse nightclub.

He says an initial "explosive breach" of an external bathroom wall did not penetrate the wall so an armoured police vehicle was driven into the wall, to "punch a hole", allowing people to escape.

He says the killer also came out of the hole, when he started shooting at officers. He was shot dead by police.